Changing someone from Client to Employee status

Changing someone from Client to Employee status

I have removed a contact as a client in a Project (I have checked and he no longer appears on my screen) and am trying to add him back as an employee in order to allow him a different view of the project. Unfortunately when I try to add him as an employee the system says he already exists as a client and won't let me proceed.

I have managed this process once with another contact and it worked the difference being that I did allow a notification to be sent.

Can anybody tell me what I might be doing wrong and if the 'non notification' is making a difference?

Also, is there a better way of moving from client status to employee?

Regards

Clive