Editing the war3map.j with MPQ-Editor

[UFC]

Hello,

i wonder what steps are to be taken in order to successfully edit the war3map.j file of a map?

I have tried making changes to the war3map.j file, removing the original file and adding the new war3map.j to the archive using the editor from here: http://zezula.net/en/mpq/download.html.

However, if i want to host the map i get an error message saying that it "cannot load map data". So i don't even get in the lobby with the map, the error message comes before that and i get back into map-selection. The original, unedited map works.
Several questions arise:

1.) In this step (loading the map data) is there any syntax-checking of the .j file done? Can it be the syntax at all? Wc3 loads for around a second before it spits out the error message, i somehow don't think it actually does a syntax check in that time (38k lines in that .j file)

2.) What else can i try? Are there certain size-limits to the .j file? Does making the file-size bigger somehow screw up the archive?

Thanks in advance!

[Regno]

Press F9 to do a syntax check in war3map.j with MPQ Editor