Help needed to setup auto tool offsets

Today I migrated from planencnc USB to LinuxCNC and things have been good so far. However I am having some difficulty setting up automatic tool offset detection. Since I am new to gcode I cant figure out what the problem is exactly.

I have tried executing following code to determine Z offset of the current tool.

option1

---

G90
G38.2 Z-10 F50
G0 Z2 F50
G92 Z27

Above one fails always saying Z-10 is not with in the limits. (However my Z axis negative limit is around -60). To fix that, I changed G90 to G91 and this error went away. However after executing the full command set, G92: Z value does not show 27 as expected.

Then I tried option 2 below again with similar results:

G91
G38.2 Z-10 F50
G10 L2 P0 Z25
G0 Z2

I expect G92:Z value to be 27, but it shows something else.

Could any one let me know what I am doing wrong here?

Also, the the button 'Tool touch Off' in axis GUI is disabled. What could be the reason for that?

Thanks

Hi suspension, there is a fine configuration example for the manual toolchange with auto z and tool lenght touch off here:
Manual tool change
pyvcp example

Thank you all.
The coordinates shown in Axis display was bit confusing so I switched to gmoccapy.
Also I changed the line G10 L2 P0 Z25 to G10 L20 P0 Z25 and it works fine now.

Tool touch off is disabled until you tell Linuxcnc to load a tool (T1 M6).
www.linuxcnc.org/docs/2.7/html/gcode/tool-compensation.html

As to your soft limit problems, I;m not sure where to start. Does your machine use home or limit switches? How do you have your homing configured? Is Z0 at the top of the Z travel?

(Edit)
Sorry, Not sure why I didn't see all the replies to the original message before I typed and sent this.