I am probably missing something very obvious, but I am having certificate problems when connecting a windows mobile.

The system is installed in SLES11SP1, and appears to be working as expected (no errors are showing). I am trying to connect a windows mobille using active sync from a windows 7 professional computer. I have installed the pem file generated from the SLES11 install onto the Windows 7 computer, but when I try to set up the exchange connection (I put a dummy domain name into the appropriate box, have the SSL ticked and just put in the ip address of the SLES11 computer) , I get an invalid certificate message showing up, and can get no further. I have tried it on non-secure, and get no error message, but cannot sync anything (I do not get any error messages, but there appears to be no login from the pda).

Anyone got any ideas how to get this working or what I am doing wrong?