heHiCreateInst() error message in sub-version IC6.1.5.500.10

 I try to create an instance in the current layout window.

 envSetVal("layout" "instLibName" 'string "myLib")
 envSetVal("layout" "instCellName" 'string "myCell")
 envSetVal("layout" "instViewName" 'string "layout")

 cdfSqu = cdfGetCellCDF( ddGetObj("myLib" "myCell"))
 change cdf values ...

 leHiCreateInst()

The first time, create instance form appears and the cell is placed in the layout. When I try this again 

X Toolkit Warning: Select failed; error code 9

appears in CIW and  create instance form does not appear. It seems to work fine with sub-version  IC6.1.5.500.6

 Any ideas?

Thanks

Labros