How do we set layers for groups

[Sannyasin Brahmanathaswami]

if the layer of fld "checkHtml" > 3 then
      set the layer of fld "checkHtml" to 3
   else
      set the layer of fld "checkHtml" to 20			
   end if

# do not work. 

stack "SlideShowSetUp": execution error at line 107 (Object: can't set layer (card not open, or control in group)), char 1

??