Stata mixed models and statsby

I am runnig a two-level multilevel model in Stata, with math students scores nested in schools.
If I want this model by districts (administratives locations) I can do it with statsby but I do not obtain
t or p for my coefficients. I know this is easy with statsby and regress extracting parameters from matrix results but how
to have p's and t's with mixed models parameters?
Thanks for your help