This is a very big graph which has size="14241,28478". I don't know how much is the limit of 'dot'. But after running dot about 1hour on a powerful machine, I get some kind of ps file which is mostly blank, only with some very long and blur dashes. I don't know what's the problem or it's simply way TOO BIG. thanks

[erg] I ran dot on the input. The result is what would be expected. The graph has size 159232 x 4678 in points. If you scale it down so that it fits in a reasonable sized window horizontally, the vertical dimensions will be so small that the graph will appear as some dashes.