Hi,
Try mentioning CSSE in single quote like this 'CSSE'. Itried like this in my example and it worked for me. you can even check the filter exprn which is applied using getFilterExpr method.
Grid.getQueryObject().setFilterExpr("[Regression_15.0/MIIOBJ/Employees2.etype] = 'Permanent'");
Hope it helps.
Regards,
Sriram