error in Quartus

First of all i would like you to apologize if what i am going to ask has been answered before.Although i searched until now i didn't find anything helpful. My problem is that when i try to compile a package in Quartus which has only components i receive the error : node instance instantiates undefined entity float_pkg. The same file has been compiled successfully in Modelsim withous changing any line.Does Altera have any forum to ask them about that? I would be much appreciated if anyone can tell me anything about that.