we don't use the commas when programming the corner breaks. also one thing the book neglects to mention is the the corners have to be 90° perpendicular to each other, so you can't break between two XZ moves and another XZ move or an XZ move and a Z move etc. the only break you can do is between a
g1 z(XXXX) and a G1 X(XXXX)
don't really know what other problem you may be running into.