How to find all the keywords saved in a file using /g when searching file contents using findstr?

Question

I have a text file (filelist.txt) with all the filenames like

a.cpp
b.cpp
...

Also a text file (projectslist.txt) with all the text files I want to search in, like:

d:\aa.vcproj
d:\bb.vcproj
... 

I am using the findstr command like this:

findstr /i /f:projectslist.txt /g:filelist.txt

This command doesn't return anything and no error either.

but the following command works perfectly fine:

findstr /i /f:projectslist.txt a.cpp

How can I use the /g option in this case?