Class not found on weblogic deployment

When trying to deploy Confluence 2.2.8 as an exploded war file, I get this error:

weblogic.management.DeploymentException:
Exception:weblogic.management.ApplicationException: start() failed.
Module: confluence/ Error: weblogic.management.DeploymentException: com/atlassian/confluence/core/ConfluenceActionSupport - with nested exception:
[java.lang.NoClassDefFoundError: com/atlassian/confluence/core/ConfluenceActionSupport]
at weblogic.management.deploy.slave.SlaveDeployer$ActivateTask.doCommit(SlaveDeployer.java:2440)
at weblogic.management.deploy.slave.SlaveDeployer$Task.commit(SlaveDeployer.java:2155)
at weblogic.management.deploy.slave.SlaveDeployer$Task.checkAutoCommit(SlaveDeployer.java:2254)
at weblogic.management.deploy.slave.SlaveDeployer$Task.prepare(SlaveDeployer.java:2149)
at weblogic.management.deploy.slave.SlaveDeployer$ActivateTask.prepare(SlaveDeployer.java:2401)
at weblogic.management.deploy.slave.SlaveDeployer.processPrepareTask(SlaveDeployer.java:883)
at weblogic.management.deploy.slave.SlaveDeployer.prepareDelta(SlaveDeployer.java:591)
at weblogic.management.deploy.slave.SlaveDeployer.prepareUpdate(SlaveDeployer.java:500)
at weblogic.drs.internal.SlaveCallbackHandler$1.execute(SlaveCallbackHandler.java:25)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:224)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:183)
No Exception Messages

I tried to look for the class and found this jar file which should presummably have it in it:

atlassian-core-2.5.1.jar

but it doesn't. Is the wrong jar file the problem or is it something else?