I am trying to run an HLM model in which monthly brand sales is my dependent variable. The model runs smoothly until I add lagged DV as a control variable in the model; when I add lagged DV I get the "r(430)" error saying "error obtaining scores for robust variance". Leaving aside the argument on the validity of including lagged DV as a control variable, is there a solution for this issue?

Even when I run a very simple model with only lagged DV included as predictor, I still get the same error.