st: margins after split-plot anova

[Luca Campanelli <l.campanelli@yahoo.it>]

Dear Stata users, 
unfortunately I can’t get margins work after anova. 

My model includes a between subject factor (group), a continuous covariate (IQ), and a within subject factor (label): 
anova depvar c.IQ  group / id|group label  label#group  label#c.IQ ,  repeated (label) 

The command: margins group
gives no results (not estimable)

The command (suggested elsewhere): margins group, asbalanced emptycells(reweight)
gives no results (not estimable)

The command: margins group, asbalanced emptycells(reweight) noestimcheck
gives results, but they are clearly unreliable; I mean, they are clearly wrong given the empirical data that I know. 

The command: margins group,  noestimcheck
gives results, but, as above, results are wrong (and slightly different from the previous command). 


If I exclude the continuous covariate (IQ) from the anova model, margins works correctly. But I’d like to keep the continuous covariate in the model. 

Any help would be appreciated. 
Thank you.
Luca


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