SCARA kinematic

i'm using the existing scara kinematic that in the system but i want to make a modification
i want to add a linear offset axis in the scara robot base which is independant of the XYZ axis
i tried to edit the kinematic with no luck 

What are you calling the new axis? Is it parallel with any of XYZ?
What changes did you make to the kinematics? It seems very likely from what you said that you got them wrong, but how do you expect us to guess where the problem is from what you told us?