Are you sure your mod tools are updated to version 1.4? I don't think a DLC3 installation would try to reference that file. If you do I would check if the file exists within raw/maps.

Oh i didnt know the...

I have a problem when i use the script placer to make a map, after i finish everything and i try to run the map it comes up with an error saying this: "Server script compile error
Could not find script 'maps/nazi_zombie_sumpf_blockers'
(see console for details)"
Please help ...