I installed a 3rd party Add_In through Tools/Add_Ins/Browse ... and then
clicked OK. The new Add_In name now appears in the Tools drop down menu.

So far so good.

Then I created my own Add_In (.xla file). I followed the same procedure as
above, but my own Add_In does not appear in the Tools drop down menu even
though its box is checked in the Add_Ins Available dialog box.

What further steps do I need to take to get my new Add_In to appear in the
Tools drop down list?

Thanks for your help ...