First: if you have set the data as panel;
Second: if the data is critically unblanced, you will loss most of the observations; you still could not get the results. You coud add some of the independt variable to have a try and then add other variables step by step.
Good luck~

First, of course....
Second, the data is not highly unbalanced...honestly i have tried two regressions, all the same independent variables. one of them can be processed pretty quickly while the other one....555
thank you anyway!