Anyone know why I'm getting this error?

[marystewart2010]

I get a nullpointerexception when trying to execute this line, which is strainge to me since it simply gets the instance:

ISessionMgr sm = CrystalEnterprise.getSessionMgr();

I'm including these jar files:

cecore.jar, celib.jar and cesession.jar

I think I have the right jars because I'm getting no compile errors at all..