Remove string from multiple filenames

I found the internet archive has a ton of old radio programs for download. I recently downloaded a number of "Yours Truly, Johnny Dollar" files. Every filename is preceded with "YTJD ". I tried using the replace action for _FILENAME
Search string: YTJD
Replace with:
(leave empty)

but the string remained. Did I miss a step?

I don't know.
It should work.
So check if there is a typo somewhere.