I want to use varmax model for an econometric research(I have 4 Endogenous 4 exogenous variable) how can I write this model is this model true?

I want to use varmax model for an econometric research(I have 4 Endogenous & 4 exogenous variable) how can I write this modelis this model true?proc varmax data=mydata;model y1 y2 y3 y4 =x1 x2 x3 x4/p=1 q=1 print all;output lead=12;run;when I write this model I get this error"eRROR: QUANEW Optimization cannot be completed"