If you're having an error similar to this one : "ERROR : extract v4.00 2012_02. Work not complete. precise vector data = 0", right click on the makevmaps_simple.bat file and hit Edit. Add this line above everything else : "cd <world of warcraft path destination>". It should look like this :
cd C:\Program Files (x86)\World of Warcraft
vmap4extractor.exe
md vmaps
vmap4assembler.exe Buildings vmaps
pause
Then, right click it and hit Run as Administrator.