Problem with [old_tool]

[Sentahopi]

As I´m trying to prevent oozing when printing with dualextruder, I´m searching for a way to get ectra rectract when old tool get´s out of work and extra extrusion when new tool is on the way of printing.

So I added this GCode in tool Change GCode:

;beginn toolchange rechterExtruder T0
T[old_tool]
G92 E0
G1 E-16 F500
G92 E0
T[new_tool]
G92 E0
G1 E17 F500
G92 E0
;Ende Toolchange rechter Extruder T0

This results in two problems: first the old tool is T-1 ???
And the second: I have this Tool Change two times instead of one and always on layer change and tool change.
On later tool changes I always get the tool change of "linkerExtruder" and no more for the "rechterExtruder"

G1 Z15.0 F300 ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded

G92 E0
G1 E-1.8 F1800
; layer 1, Z = 0.35
;Start Toolchange linker Extruder T1
T-1
G92 E0
G1 E-16 F500
G92 E0
T0
G92 E0
G1 E17 F500
G92E0
;Ende Toolchange linker Extruder T1T0
; tool H-1 W-1
M106 S0
;beginn toolchange rechterExtruder T0
T-1
G92 E0
G1 E-16 F500
G92 E0
T0
G92 E0
G1 E17 F500
G92 E0
;Ende Toolchange rechter Extruder T0
T0
; tool H0.35 W0.6
G0 X90.278 Y126.206 F3600

Thank your for your help!