IF_HTTP_CLIENT->RECEIVE 1 ICM_HTTP_SSL_ERROR

Dear,

I have an issue with the SSL connectivity in tcode OAC0.

When I send the certificate it gives me the "Certificate sent succesfully"

When I try to test the connection though, it gives me:

Error in HTTP Access: IF_HTTP_CLIENT->RECEIVE 1 ICM_HTTP_SSL_ERROR

I got a bit stuck on this as all the ssl is configured

Any ideas what to check (or check again)