Options tab has disappeared [SOLVED]

In OpenCart 1.5.6.4, following upgrade, the Options tab under Catalog has disappeared. Products to which I had previously assigned options are still showing those options on the product page, but I can't edit those options or add new ones. How can I re-enable Options?

ETA Now sorted out. I uninstalled all my extensions and reinstalled them one by one. The problem lay with No-Advanced.xml, which obviously isn't compatible with OC 1.5.6.4.

Hi niroc,

Can you mark this as solved in the heading?

- Mel