Data Validation Warning Message

newdoverman, thanks for your suggestion and thanks as well to EleGault and davesexcel for your suggestions. I decided to try newdoverman’s suggestion first as it seemed the most appropriate for my needs. Although his suggestion works perfectly in the sample I downloaded, when I attempt to recreate it, everything appears to work as designed, however, once a selection in the data validation list is made, the selection remains visible in the list and if I understand the example properly, that selection should be removed from the remaining available selections.

When I downloaded newdovernan’s example it worked in that once a selection was made from the data validation list, that selection no longer appeared in the list of available choices which is the solution I am looking for.

I’ve uploaded a sample spreadsheet that demonstrates where I attempted to replicate the suggested layout and formula. Perhaps I made an error when I recreated the example and one can take a look to advise as to why my recreation was unsuccessful.
I will await a reply to this post before trying EleGault’s or davesexcel example. Thanks again everyone.