Alien Swarm Map Overview Trouble

[PhortyTwo]

I'm making an Alien Swarm campaign called Dash. If any of you would like to test the maps without an overview or a radar, please PM me.

So, here's the deal:

Okay, so I've got the correct transparent .vtf for the vmt available at:
[URL]http://developer.valvesoftware.com/wiki/Deadline_vgui_.VMT_File[/URL]

Which I'm using for:
[URL]http://developer.valvesoftware.com/wiki/Swarm_Overview_Map[/URL]

Now, I've configured my map1.txt Overview file in /resource/overviews/

to point to the map1.vtf, but no matter where I put it in my addon's folder, I end up getting a texture error on both the radar ingame and the briefing before the game starts. Where do I put this file, and how do I point my overview text file to it?