Got an answer from Stuart. He said my 'CONV_ID' and 'CONV_GALLERY_ID' were wrong and gave me the right ones from my database.
In the end it looked like this:
// THE CONVERSION ID
// This would have been asked for when setting up the converters
You can find the CONV_ID and CONV_GALLERY_ID name, which you'll need, in the database table 'conv_apps'.