Encrypted SSL Certificate

[Christoph]

Hi there,

I want to install an encrypted SSL certificate for one domain in Plesk.
An error occures while installing this certificate. It's called "Unable to set the private key: Probably, the private key format is invalid.".
I thought this happens, because the certificate, especially the RSA private key, is encrypted. Is that possible?
Is it possible to install an encrypted certificate in Plesk?

Any ideas?

Christoph