I am working on wide formatted data that have 11574 observations &11547 row. the repeated observations is for prescription issuedate as every patid has multiple issue date. I need to work on the data to identify gaps of 90 days between issue dates, therefore I want to transform the data to long format. this is an example of my data

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input double(patid issuedate_n1 issuedate_n2 issuedate_n3 issuedate_n4 evdate_n)
 20018 19842 19792 19766     . 19751
 820018 18596 18666 18596 18714 18650
 220018 21090 20681 20893     . 20879
 720018 21010 21158 21183 21273 20944
 620018 20216 20010 20451 20023 20149
 720018 19715 20023 20072 19876 19771
 420018 19451 19201 18756 19430 19102
 820018 19493 19481     .     . 19452
 320018 19250 18919 19250 19023 19126
end
format %tdCCYY/NN/DD issuedate_n1
format %tdCCYY/NN/DD issuedate_n2
format %tdCCYY/NN/DD issuedate_n3
format %tdCCYY/NN/DD issuedate_n4
format %tdCCYY/NN/DD evdate_n
I tried this code [reshape long issuedate_n, i(patid) j(littlen)]

and got thie error � invalid name
r(198); t=1138.64 0:08:20

can you please advice how to transform this data and identify the gaps for each pat ID ?
This my first post I hope I made it clear