"Error: Unable to write on "assets/mods" directory." When loading mod.

I've been in the process of starting work on a mod, however I have encountered a bit of an error, when trying to activate it via mod launcher it will will give the error:

Error: Unable to write on "assets/mods" directory.Check program's permissions.

As far as I can tell everything in the files for the mod is set up correctly.

I've been in the process of starting work on a mod, however I have encountered a bit of an error, when trying to activate it via mod launcher it will will give the error:

Error: Unable to write on "assets/mods" directory.Check program's permissions.

As far as I can tell everything in the files for the mod is set up correctly.

It's either the launcher being buggy (as per usual), or it's something up with the file.

Either way: having a copy of the file would help us double check for you...

I believe it has to do with the file, I actually had managed to fix this error with the first weapon I had added in, but the second one I've made has had the error again. This time I can't see anything wrong with it at at all.

http://www.mediafire.com/download/5cdivlgl99hvl17/ExpandedBallisticArsenal.zip

Here is the zip file of what I have, the only added thing are two weapons: One is a PKM using the PKM image found in the game files, and the other is an FN FNC. I believe the FN FNC is what is having the error, as before adding it I was able to stop this error from happening.

Also, after saying the whole "cannont write to assets/mods" thing it will bring up another small window saying it cannot find the png for the FN FNC, but it very much exists.

As mentioned I had fixed this error with the first weapon I added, but since adding this second one it has returned.