I've developed, in Excel 2002, a VBA form that uses a Calendar Control
to pick dates.
On SOME Excel 2003 users in the office, but not all, they get an error
trying to load the program (it's a time-sheet program), which says
that an object is unavailable.

From some research to date I have a sense that the issue lies with
references made to Office 10.0 and Excel 10.0 Object Libraries on my
2002 version, and perhaps the calendar control is different in the
11.0 versions, but frankly, I'm getting out of my depth at that point.

Are there some key steps I can take to properly diagnose the
"unavailable object library" ? In particular, is there then an obvious
remedy. like copying some librayr file from my Excel 2002 PC to he
users' Excel 2003 (or 2007) PCs?