Copy mail with CDO objects

Situation :
A customer of ours uses the NAV email logging. With the Queue and the storage folder. But, NAV only logs mails from known contacts. They said they wanted a folder where they could copy mails into after they added a new contact.. And they wanted to log the mail history they had build with this contact.

Solution ( or so i tought) :
Let's take the email logging codeunit, copy it. Copy all the necessary fields in the RM setup to store a folder ( name, store & entry id) ... Set it up, adjust the codeunit to the new folders... let it copy from the new folder to the queue folder and the default e mail logger kicks in and my work is done... Hell no, I keep getting errors from the cdo objects and i cannot see what i have done wrong!

I get the next errormessage on the next line
CDOStorageMessage := CDOHandler.CopyTo(CDOQueueMessage);

Errormessage :
=================================================================
This message is for C/AL programmers:

The call to member CopyTo failed. Collaboration Data Objects returned the following message:
[Collaboration Data Objects - [E_INVALIDARG(80070057)]]
=================================================================

Anybody any idea ?