How can I mix a percentage of down elevator when throttle is is increased?

[Crunch69]

How can I mix a percentage of down elevator as the throttle is is increased?

I tried this mix without any luck
CH02 : ELV [IO2] ELV Weight (+100)
+=[IO3] THR Weight (-17%) NoTrim Diff (100%) [DWNELV]

[lancaster]

This is my setup

CH2 source Ele wt 100
source OP7 wt 50 switch ID-
CH3 source Thr wt 100
CH7 source Thr wt 100 offset 100
source P3 wt -100 multiply

ID switches on elevator trim and throttle linkage
P3 varies the amount of down trim that is applied by throttle