You might consider using this:
_ps = new PaletteSet("AXYZPalette", "", new Guid("45fb0c44-3ede-48c2-838e-98d742d1b4a9"));
Mind the extra parameter in the middle. This way AutoCAD does not try to run a command named after your Palette. If you don't use the middle parameter then AutoCAD will run the command AXYZPalette, even if it is not created.