How to fix returning of the first value in a column instead of the appropriate value using VLOOKUP in Google Sheets?

Good afternoon Please give advice.

In this screen, "C9" is a drop-down list of "A" values. "D9" is the result of the "VLOOKUP" function. In "E9" I need the index of the value "D9" from column "B". But the problem is that it always returns the first value in the column. As on a screenshot it should return "B6".

Is the a way of solving this problem? Thank you.

enter image description here

I tried this code:

=ADDRESS(MATCH(VLOOKUP(C9;A2:B6;2;FALSE);B1:B6;0);2;4)

>Solution :

You may try:

="B"&xmatch(C9,A:A)