You might try
this for Vector TDx instead, though I have no idea why or if that would work better (the /ca in the other link makes me wonder if it's regional).
I've tried a very little bit of TDx, and it looks brutal. The cash is doled out the same as the Hard maps in TD, and the enemies have substantially more HP (though now that I look at it again, the inflation on their HP is less steep -- only about 10% from wave 1 to wave 2, rather than the 20% you get in TD).
[Last edited by NeonElephant at 11-17-2007 04:16 AM : more notes on enemy HP in TDx]