Dears,
I am trying to establish GMM analysis for a paper but I am unsure if it is correct. The original OLS reg model is as follow:
FP = PostCSR + CSR + Post + Controls

Where,
Dependent var = FB
Indep. var = PostCR (CR after a specific year, & the year is dummy 0,1 )
Control var = SGAt1 RDIt1 CGt1 LnAget1 Sizet1 Levt1 IndSenst1 betat1 TQt1 (t1 = one lagged year)
Instrumental var= MedCR Lnage

I established the following codes and each one gives me different results, I need the overidentification tests (sargan and Hansen tests) which I couldn't obtain using the first code:
1-
Code:
gmm (TobinsQ- {xb: RegCRt1 CRt1 Regt1 lambdat1 }- {b0}), instruments(SGAt1 RDIt1 CGt1 LnAget1 Sizet1 Levt1 IndSenst1 betat1 TQt1)
2-
Code:
xtabond2 LnTobinsQ l.LnTobinsQ LnCR Reg LnSGA LnRDI LnCG LnAge_w Lnsize LnLev LnTQt1, gmm(l.LnTobinsQ LnRegCR) iv( Med_CRt1 LnAge_w) twostep robust
I read almost all related documents to those commands but I couldn't understand how it should be built correctly. Please advise how it should be built? shall I lag all the variables? the overident results should be always accepting the null to make sure that my model is correct, or it is OK if not?

Thank you in advance