ISE14.7进行后仿真的时候总是报ERROR:Simulator:702 – Can not find design unit work.glbl in library work located at isim/work

请问我用ISE14.7进行后仿真的时候总是报ERROR:Simulator:702 – Can not find design unit work.glbl in library work located at isim/work
是什么原因呢，我也试着把glbl加进去可是每次一运行就丢失了