Invalid File Error - fixed (:[SOLVED]

So, I replaced all the files in the installation folders with the clean files from the Ultimate Fix.
But despite replacing all of them (and the Generations/TLS/Pets one in the basegame folder) I STILL get a "Invalid File Error" when trying to patch from 1.24 ):
Is there something I'm doing wrong or is the game just hating on me?

Thank you in advance

ETA:
I looked up the rtpatch.log and the file which is causing this error is TS3.exe, even though I definitely replaced it with the Ultimate Fix version.
???

ETA2:
Managed to fix it myself!
Here's what I did for anyone else having the same problem:
The issue (as far as I can tell) is that replacing the files causes it not to be seen as version 1.24 anymore. So what I did was get the 1.24 patch and install it (there are several places you can get old patches, simswiki.info is one) and THEN install the 1.26 patch. It didn't give me the error so it seems to have worked.