fixed bug introduced into null/test4.xml that prevented it from running.
fixed bug introduced into null/test4.xml that prevented it from running.

rwcarlsen/cyclus,gidden/cyclus,rwcarlsen/cyclus,rwcarlsen/cyclus,gidden/cyclus,Baaaaam/cyclus,hodger/cyclus,Baaaaam/cyclus,gidden/cyclus,hodger/cyclus,mbmcgarry/cyclus,mbmcgarry/cyclus,Baaaaam/cyclus,mbmcgarry/cyclus,gidden/cyclus,mbmcgarry/cyclus,hodger/cyclus,rwcarlsen/cyclus,hodger/cyclus,hodger/cyclus