testing for heteroskedasticity in VECM

[Hamid muili]

In estimating time series Vector error correction model in stata using the Vec command, i observe that the only post estimation diagnostic the stability, autocorrelation and normality test is the available post estimation test. is there a way to test for heteroskdasticity too. just as it can be seen in other software like Eviews. i tried using estat hettest, but it shows invalid.