[Skunkworks] Blackberry not connecting to corporate email - Exchange

Hi skunks. I have some blackberries and Nokia's thet i have configured to access corporate email on Exchange 2007 Blackberry: Blackberry Internet Services. Nokia: Mail for Exchange / Activesync. My issue is that Nokias can access using SSL Blackberry Internet Services CANNOT... it refuses to acknowledge that mail.domainname.co.ke is a valid server. The BB has other valid accounts on gmail, yahoo. I can use /owa on any browser including the BB's WAP browser. Am sure its a certificate issue on BB, just not sure why it should reject completely. On Nokia it gives a security warning, i accept permanently For BB, am stumped. Any ideas? Thanks. /.Sam