[RMVX] Anyone familiar with SwapXt? Need some help.

I downloaded SwapXT from here (http://www.rpgmakervx.net/index.php?showtopic=33958) but I've encountered a problem with it; but the creator doesn't seem to respond to issues and the thread is pretty dead, so I'm pretty lost! Any help would be appreciated. Here's my problem:

I downloaded the script and the application. I copied and pasted the script into my game and created a "test" map to fiddle around with swapext. I created a basic map with tilea1.

I then opened up Swapext, loaded the game, and swapped tilea1 to the new tilea1 (let's say newa1 from now on). Accordingly, the map I created on the editor changed to reflect the swap.

As per the video tutorial bullet posted, I went to the third tab and and hit "apply current tilesets/passages to VX Map ID" and selected 1, as that was my only map. It now reads Map ID 1 and the only swap info is Tilea1: newa1, as it should be.

Following the video, I then selected Reset all Tilesets to default and the map on the editor changed back to the default - but according to the video, when you go to play, the map should still be swapped to the new tileset. However, I went to go play, and it had reverted back to the old tileset.

I've tried this using two maps, swapping ID 2 to the new tileset but keeping ID 1 default, but no matter what, whenever I go to play, the game doesn't reflect the swap, and I certainly have used the third tab on the program to apply the tilesets to the Map ID. I've followed the directions on the video tutorial exactly.

What am I missing? Thanks for any help.