In the CUI, in the upper-left pane, ensure that in the pull-down box at the top, that "ALL CUSTOMIZATION FILES" is the current selection.
Expand the "WORKSPACES" tier, and highlight the (current) workspace, whatever it is called.
This will show the contents of the Workspace definition in the upper-right pane of the CUI.
Expand the "MENUS" tier of the list of contents.
Do you see your custom menu in this list?
If Yes, uh.... /shrug
If No, then in the upper-left pane, (with your workspace still highlighted, to ensure your upper-right pane still shows it's contents), expand the "MENUS" tier, find your custom menu, if it exists here, and drag it over to the "menus" listed in your workspace.
Did this help?