I'm running on this code below to do regression on stock data by combination of industry and year.

Code:
gen gics_2di =(gics_code-mod(gics_code,10000))/10000

egen code = group(ticker)
tsset code year

//***ABACC

gen ta_a = ta/l.totassets
gen a_1 = 1/l.totassets 
gen revchange_a = revchange/l.totassets
gen ppe_a = ppe/l.totassets


rangestat (reg) ta_a a_1 revchange_a ppe_a, by(gics_2di) interval(year -15  0)
However, there are missing coefficient values for some stocks (in the example, the missing coefficients lies in ticker AAM)

The data and result should be like this:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str5 ticker float(year gics_2di ta_a a_1 revchange_a ppe_a) double(reg_nobs b_a_1 b_revchange_a b_ppe_a b_cons)
"AAA" 2003 15            .             .           .         .    .                  .                  .                    .                    .
"AAA" 2004 15            .             .           .         .    1                  .                  .                    .                    .
"AAA" 2005 15            .             .           .         .   25                  .                  .                    .                    .
"AAA" 2006 15            .             .           .         .   56                  .                  .                    .                    .
"AAA" 2007 15            .             .           .         .   92                  .                  .                    .                    .
"AAA" 2008 15            .             .           .         .  137                  .                  .                    .                    .
"AAA" 2009 15   -.05188835 3.6855293e-12    .5019693  .8268633  202                  .                  .                    .                    .
"AAA" 2010 15     .2088325  2.294363e-12    .6763351  .8757771  278  1584085939.736831 .12708950132613406   .05657954920865471  -.07968150937740576
"AAA" 2011 15   .012144913 1.5504392e-12    .3586467  .7700721  357 1653130186.7238574 .12304488450062984   .04250903784775931  -.06838153326464892
"AAA" 2012 15   -.06748654 1.2245628e-12   .12172044  .6552734  439 1796246290.7076917 .10843686785100161   .03259520754244283  -.05762622365820059
"AAA" 2013 15   -.03477767  1.110502e-12   .16377077  .8288529  528 1855507585.5310318 .10484449294948195    .0081626947382177  -.03851675489681643
"AAA" 2014 15   -.05060567   8.69135e-13    .3503795   .764523  621 1820172009.2382293 .10735836019288442  .008632049216262948  -.03404546181289806
"AAA" 2015 15     .0728228  7.034077e-13   .03791743  .7684436  725 1844540524.2672079 .10502553909163503  .004908517100251392  -.03251337769978387
"AAA" 2016 15    .02589748 5.1157055e-13    .2707338  .9813811  834 1840205714.4097126 .10291879354879138 -.002550035728466571  -.02461432340197646
"AAA" 2017 15    .10771796  3.249268e-13    .6257566  .9116007  947 1818594860.0648074 .10406992428809676 -.005796115008249517  -.01847536830811619
"AAA" 2018 15    .03279573 2.1852397e-13    .8614137  .8886017 1063 1905972664.3830402 .09622948327168132   -.0119113933157124 -.012175509251885111
"AAA" 2019 15   -.01036422 1.3281683e-13   .16555625    .43516 1181 1925427312.0034378 .09591158063414375   -.0166303016195546 -.011054076888552093
"AAM" 2004 30            .             .           .         .    .                  .                  .                    .                    .
"AAM" 2005 30            .             .           .         .   15                  .                  .                    .                    .
"AAM" 2006 30            .             .           .         .   40                  .                  .                    .                    .
"AAM" 2007 30    1.0831021 1.4571764e-11   .12244625  .6022781   67                  .                  .                    .                    .
"AAM" 2008 30   -.06497576  3.214369e-12   .16566242 .17546953   99                  .                  .                    .                    .
"AAM" 2009 30    .04947018  3.326073e-12    .2157253 .25924137  140                  .                  .                    .                    .
"AAM" 2010 30    .10391025  2.747744e-12   .10173995 .24104966  184                  .                  .                    .                    .
"AAM" 2011 30    .06985304  3.018082e-12    .4191923 .25240043  228                  .                  .                    .                    .
"AAM" 2012 30   -.04962417  3.030517e-12    -.465879 .23865224  273                  .                  .                    .                    .
"AAM" 2013 30   -.04462884  3.499432e-12   .16769205 .27919668  322                  .                  .                    .                    .
"AAM" 2014 30   -.04268124 3.3104745e-12   -.3127411  .2606126  371                  .                  .                    .                    .
"AAM" 2015 30   .008665917  3.364839e-12   -.3007686  .2676917  422                  .                  .                    .                    .
"AAM" 2016 30 -.0012889402  3.106229e-12  -.23250994  .2457513  475                  .                  .                    .                    .
"AAM" 2017 30    -.2301546 3.8774153e-12  -.19615464   .318954  533                  .                  .                    .                    .
"AAM" 2018 30   -.05868362  3.975185e-12 -.023554154  .3396268  592                  .                  .                    .                    .
"AAM" 2019 30    .13503978    4.3486e-12   -.0093145  .3804228  651                  .                  .                    .                    .
"AAM" 2020 30    .04339687   4.39545e-12   -.4186026  .3865967  708                  .                  .                    .                    .
"AAV" 2004 60            .             .           .         .    .                  .                  .                    .                    .
"AAV" 2005 60            .             .           .         .    4                  .                  .                    .                    .
"AAV" 2006 60            .             .           .         .   11                  .                  .                    .                    .
"AAV" 2007 60            .             .           .         .   27                  .                  .                    .                    .
"AAV" 2008 60            .             .           .         .   47                  .                  .                    .                    .
"AAV" 2009 60            .             .           .         .   75                  .                  .                    .                    .
end
Please help me figure out the issues and recommend some solutions. Thanks.