"You have data in your column in that table that no longer fits in the new definition"

The data in a table that uses one of those domains has only one record, I do not alter that record at all (some document type name default defined). 

I create many temporary tables in runtime (with random names) and drop those when I leave / close the database. Can this be the problem ? 

but I use this structure / program at many other customers ... No problem there.

Anyway, if GBAK could backup those domains (with huge names), why , the same GBAK, could not restore those with the same name ? 

Tiberiu