I'm currently using this script and importing the dynamic stamp in to Adobe Acrobat.
event.value = (new Date()).toString();
AFDate_FormatEx("h:MM tt, mmm dd, yyyy");
How did you import the stamp, exactly?
You should not import an existing stamp. Instead, you should copy the stamp file as is from the Stamps folder in the old machine to the new one.
There's no universal definition of how stamp files should work. I guess the BB stamps don't follow the Acrobat pattern, so you will have to re-create it in Acrobat. You can reuse the same code, though.