error on node page (field group)

warning: Invalid argument supplied for foreach() in /sites/all/modules/cck/fieldgroup.module on line 394.

I get this error on my node page (test site). I use field group in one cck content type, though I only have one field in that field at the moment. On my node page, one cck node from that node type is displayed. When I click on that node, no error, ir only displays on the node page.

Anisa.