Something doesn't add up. If you're calling fetchrow_arrayref, then your print example should show ARRAY(0x123456) or some such. That error message you're getting indicates the actual value (not a scalar ref or an array ref) is contained in $newUID, which is not consistent with the return value from that method.

Stop, take a deep breath, make sure your code says what you think, and then go through brian's Guide to Solving Any Perl Problem.