Help - Cannot search PDF files

Running DO ver 12 on Windows 7 64 Pro.

I am searching directory trees for a specific character string and I am finding that the search skips over all PDFs in the tree. I absolutely KNOW that the string I am searching for is in multiple PDF files, but the search turns up nothing in PDF files and multiple hits in non-PDF files.

If I actually mandate filename = "*.pdf" the search still turns up nothing.

Please advise. Thanks.

Please post a screenshot showing how you have configured the search.