Hi
I run the Heckman two step selection model by using following stata code. I am using stata 15.1 v.

heckman DV IV control_cariavle i.year i.industry , twostep select(IV = x2 x3 x4 x5 x6) rhosigma vce(conventional) first

After running the code, in first stage coef has value but Std.Err, z, P>|z|, [95% conf. Interval] does have any value. Please see the image below.Array

In second state after the regression result, I found the following result and got blank value. Can anyone help me how can I solve the problem.Array