Some time ago, we came up with a task that involved one of our people changing a custom property for a whole bunch of drawings in EPDM to all have the same value, so I wrote a little program in C# that would check out all the files, change the custom property and check them all in again. Just recently I had to make a small change to it because the EPDM workflow changed, but when I recompiled it, it no longer works. The bit I changed has nothing to do with the bit that isn't working.
I get a list of files to change via a drag and drop interface, then iterate over the files to remove the ones that are already checked out. I end up with a List<EdmSelItem> called checkedInFiles. From there, I'm trying this: