OK. I'm not sure what the answer is so here are some questions to try to narrow it down
1 - what version of xbmc are you using... and are you sure. I recommend you make sure you are using Dharma beta 2 or Dharma beta 3.
2 - are other simple xbmc commands like stop, play, up, down, etc. working?
3 - when you try to run GenXML is this error occurring for any and all types of data? (i.e. artist, album, songs, tvshows, movies, genres etc.?)
let me know, and we'll try to go from there.