Flipping Dimensions/Parameters CREO 9

Hello all i do have some Problems questions in understanding Sensitivity Analyses and Cordinate Systems

What i have is the Default CYS and an Offset CYS that i create i control its Origin with Paramets as follows

X=200

Y=200

Z=-200

the relations i use look like this :

$d3=X
$d4=Y
$d5=Z

when i now start and run an sensitivity Analyses for Parameter Z with a minimum Range of -220 and maximum of -180 it runs though.

but when i recheck my Parameter for Z it has changed from-200 to +200 and the Coordinate has flipped its Position. 

is it possible to avoid flipping Parameters or Dimensions i don't want the minus to disappear?

can someone relate and help out?

Kind Regards

Markus