does it work if the target version is 8.1. or higher, and strictscoping is enabled?
Does it work at all, or just in this one case where you set the compatibility target version to be 8.0 or higher (Guessing, since you didn't specify) that it doesn't work?
I saved the form to be compatible with version 7.x and higher. The form works fine with adobe acrobat, adobe x, etc. but not with adobe pro 8.
How do I turn on strictscoping?
Depending on your Designer version (no longer able to set it in UI in Designer 10, for example), strictscoping is set in the form properties of the form (File->Form Properties->defaults).
However, since this is just happening in Reader 8.0.0, it sounds like you hit a bug in that version.
FYI: Support for Reader 7.x, and Reader 8.x have been end of lifed by Adobe.
Best bet is to use Reasder 9 and above if they work, and it sounds as if they do.