Class Type Not Specified Error

Hi,

One of our users is unable to carry out an 'Approve' action on a change task. The error he receives says Class Type Not Specified. See below:

I have tried numerous ways to fix this and have searched the forums here to see if anything similar has ever come up.

Unfortunately, Im no DBA, and dont really understand what the error is telling me.

Any help appreciated.

Thanks,

Martin