Hi Tunbers,
What version of Numbers is attempting to open the file on your Mac? Choose About Numbers, the first item in the Numbers menu. It will say 1.x, 2.x.. or 3.x..
The first two cannot open files saved by the current versions of Numbers. The third can.
What version of OS X are you using? Numbers 3 (the new version) requires Mavericks (OS X v10.9).
If you recently updated Numbers from the Mac app store, you may have two versions installed on your Mac. That's not in itself problem, but it is something you need to be aware of and to deal with.
If your prime concern is compatability between versions on different devices, then you should be using version 3. Control-click (or right click) the file, and choose Open with...Numbers 3.
If you have documents created on your Mac that use features available in Numbers 2 (or 1) that are not or not yet available in Numbers 3, then you may want to continue using Numbers 2 (or 1) for those files. Opened in Numbers 3, they will lose any features unsupported in that version. Saved from Numbers 3, that loss will be permanent, and the files will no longer be openable in Numbers2 (or 1).
Regards,
Barry