Hi,
I have an unbalanced panel dataset. I'm receiving this error message "numlist in operator invalid" while running the following regression using "sureg" command. i.date and i.userid are used to work as FE.


Here is the regression I am running:

sureg (y1= x1 x2 x5 x6 i.userid i.date ) (y2= x1 x2 x3 x4 i.userid i.date), isure



I'd appreciate if someone could help me to fix this problem.

Thanks in advance.