Touch off not zero?

Hello
For some reason when I touch off the axis on a lathe I cant set it to zero, when I set it to zero it will be 0.12 for example??
The setup is Mesa 7i77 with analog servo control and the encoders have 2000ppr

this can also be caused by incorrect entrys in the tooltable
also you may find you need to correctly set the index point of the encoders to the same as home , the small amnount you show
this is probably the main problem , easy way is to home , and then slacken off the encoder mount screws and slowly rotate the encoder to get zero , so zero of the encoder matches your zero point , you could also set an offset value in your ini .
although i personaly prefer to adjust the hardware .

but make sure you dont have any values from tooltables or values in your config first

Thanks for the answers, I will try your suggestions and get back to you.

(its touch off for the coordinate system)

The simple solution was to set HOME = value opposite the error ie if error is 0.2 set to -0.2 (in the INI file)