IPP creates invalid Certificate Signing Request

iPhonePackager produces a Certificate Signing Request file…

"Running OpenSSL to generate certificate request…

… Successfully generated certificate request"

But when trying to add an iOS Developer Certificate the apple developer site says the .csr file is invalid - but no hint as to what the problem is. Have been round in circles for a couple of days without success.

Running on Windows so not obvious alternative route for gaining a Certificate.

Any thoughts?