Problem opening a Numbers file on new MacPro
I just purchased a new MacPro with Mountain Lion. I moved a hard drive from my older MacPro to the new one. I installed iWork 8 on the new computer, then installed the update for it. I tried to open a document that I created in iWork 8 on my old computer, but a drop-down box said that I "need a newer version of Numbers to open this document."
Can someone explain what is going on?
Mac Pro, OS X Mountain Lion (10.8.2), 3.33 GHz 6-Core IntelXeon, 8 GB RAM