Everytime I package my project I get a error

As I mentioned (I got it to package but this message keeps popping up (PackagingResults:Warning: Warning Warning Unable to find package for cooking /Game/Maps/Menu)

I can’t open the packed file.)

I was finally able to package the file thanks to you and saeedc, but I can not open the packaged file. I tried repackaging it a couple of times. I can’t think of anything else.