Mod map is missing file/broken

Hey! Im new to the forum ive just joined because i cant seem to figure out a problem and ive seen a lot of helpful people on here thus far..

So ive made custom maps before (just basic ones to drive around on with modded vehicles) so I have an idea how to use the editor and everything but ive decided i want to try to implement my own 3D models into the maps, things like RTI ramps, Blocks to climb.. ect.

Ive followed this older tutorial by DigitalX -
and its pretty easy to follow.

Ive also seen other posts from DigitalX with some other updated steps etc..

Here is my basic cube i made -
Heres the error I get trying to load the level -

I only get that error after adding my cube. If i remove it and try to play the level it works perfectly fine.. Any help is highly appreciated.

PS. Sorry if this is in the wrong place, I just joined the forum so im not sure where it should go.

Are you loading your map through the Proving Grounds?
In broad terms, you need to have the mesh and XML files for your cube in the corresponding game directory, not just in the editor. The map loads when the cube is not present because all of the default resources are already in the game directory.