Can not "Build-up" the XWIki Training group collection in IE get JS error

Happens on Next, Staging and Prod, but not with other collections.

Try and build up this collection using IE 7: http://next.dev.curriki.org/xwiki/bin/view/Group_XWikiTrainingGroup/Curriculum

When going to SRI 1, you see a JS error: Ext.getCmp(...)getNodeByID)..._ is null or not an object

When you complete the add, the resource is added, but not into the group collection space.

Other group collections do not have this issue, so it appears to be something about this group. Other groups might have the same issue, but I have not found one.

(Dave, pass to Ludovic it the cause is not evident.)