When I ran the xtgls regression:
Code:
xtgls dep var, covariate 1 covariate 2 .....covariate n, corr(ar1) panels(hetero)
I get this error message:
Code:
time is not regularly spaced or does not have intervals of delta -- use 
the force option to treat the intervals as though they were regular
r(459);
What could be the issue and how can it be addressed?