Private key problem inTN


I want to add a private key (.der) into the verify/sign tab of my own profile in TN in order to send out signed EDI documents to our client. But when I add the document I always get the following message

“The private key you tried to import is not valid.”

Did I create the wrong private key or am I doing something else wrong.
I already installed the public certificate in the partner profile and I can send out encrypted documents, it is just the signing that gives problems.

Can anyone help me pls?

Did you upload your public cert, into your enterprise profile? If you did, than looks like the private key you are trying to upload is not the right one, i mean it to say, it is not the one used to generate your certificate.