Just off the top of my head, I do not see a connection made to the database. This would seem to be borne out by Access denied for user: '@sb-desktop.local.server.com' (Using password: NO) at MySQL_queryDB.pl line 5, where the user name should come before the "@sb-desktop.local.server.com" (ie should be "testuser@sb-desktop.local.server.com"
Check the NET::MySQL docs (if you want to stay with this package) to make sure if a connect command is needed. I suspect that that is going to be the case.