model = lmer(y~.,data = data)
step(model)

> step(model)
Error in model.frame.default(data = AUC_dum, drop.unused.levels = TRUE,  :
variable lengths differ (found for 'c("Time_Three + Time_Six + Time_Nine +
Num_Semester_Five + Num_Semester_Four + Num_Semester_Three + DataBase_Uni +
Num_Semester_Three:DataBase_Uni + ",      " # **<-- What is this????**
Num_Semester_Five:DataBase_Uni + Num_Semester_Four:DataBase_Uni")')