Double check that you performed the configuration for shared libraries for rs.war.  From the Interactive Upgrade Guide:

"8 Update JRS shared library classpath Back to top
a.    In WebSphere Integrated Solutions Console navigation pane click Environment > Shared libraries.
b.    Click the JRS shard library name in the list to open it.
c.    In the Classpath field, update the path to the new installation directory. For example:
D:\IBM\JazzTeamServer6.0\server\conf\rs\WAS_SharedLibrary
d.    Click Apply and then Save directly to the master configuration.

15  Configure the Report Builder application Back to top
a.    In WebSphere Integrated Solutions Console click Applications > Application Types > WebSphere enterprise applications.
b.    On the Enterprise Applications page, in the list of resources, click rs_war.
c.    On the Configuration page, in the References section, click Shared library references.
d.    Select the rs_war check box and click Reference shared libraries.
e.    In the Available list, select JRS Shared Library and click the right arrow.
f.    Click OK. Click OK again and then click Save.
g.    In the list of resources, click rs_war.
h.    On the Configuration page, under Detail Properties, click Class loading and update detection.
i.    In the Class loader order group, ensure that Classes loaded with local class loader first (parent last) is selected. Click Apply and then click Save."