Batch rename doesn't work with slash characters

Has anyone found this issue ? I have a number of files with dates in their names. I've used diagonal slashes in the dates like this:

File 1 - 23/2/12.pdf

File 2 - 24/2/12.pdf

When I try to batch rename those files, it gets confused by the slashes - it tries to rename all the files as "16.pdf". It can't so it pops an error after the first file. It looks like this before - notice that the example is wrong - Finder has trimmed off all of the file name except the "16.pdf":

Afterwards, it looks like this:

It has renamed the first file by removing all but the changed text but can go no further.

I know that slashes are not always permitted in file names but, this is the first major issue I've found. Any ideas ?

Thanks

Garry