In the CIW, can you try do this (with the schematic open for edit):
does it return anything?
I have seen one case where the check above (actually it was for an iterated instance) returned nil, and I had to do (at the UNIX level):
oaScan -lib libName -cell cellName -view schematic
which reported an issue with the database, and then I called it again with -repair to fix it. Note that you need to have the schematic closed in the editor to be able to run oaScan.
But most lilely it is that you really have an instance called K0 somewhere...