Because, after the game updates in the middle of this year, the GWA file in the bots of the first page are outdated and needs some upgrade.
You can do it in a couple of ways:
- Use the "Guild Wars Botting API Patcher" made by rheek

- grab a new up to date GWA, the one by tjubutsi is perfect
You need to read at least the first 90 pages of this post if you want to undestand how thing works, be aware that in this forum a DIY is strongly encouraged.
Here the bot up to date (leave the passw box clean), use the white brass knucke, if you use the gold one remember you need at least 9 in dagger mastery.
Cheers.