1. Please read the thread I gave you that is EXACTLY what that script is for. It checks your forum for the userid of a person based on there username and updates photopost with the proper userid.
2. You need to set the proper path to mogrify in config settings or on the server or set the processor to GD2 in global options.
3. You need to use the proper configuration variables to retrieve the information from vb
. The error suggests you have not.