[TSVN] Changed binary not shown up as changed

Today my collegue had to change one of my scripts stored in the
subversion repository. (v.1.1.3 Subersion and TortoiseSVN)
but afterwards it didn't worked anymore. I figured out that a change to
a binary file wasn't checked in to the repository. So i changed the
file again but tortoisesvn didn't noticed it as a change.

So my question is: How does Tortoise checks for changes in binary files
(we are talking about a 6 KB .exe file) or is there a possibility to
force tortoise to change the file in the repository? One single changed
character in a text based file was instantly marked as changed.

The file we are speaking of is a dialog from the nsis distro which i
edited with the resource hacker. So ca. 20-50 were changed.

Regards

Sebastian