Cloth Bind Settings per Material ID possible?

[olika3d]

errr... those times you fail right at the start of your project...

I have this balloon with two Mat ID'S on it (grey and dark grey)
and would like to assign different cloth bind values to it.
I.e. make the darker straps stiffer than the rest.

But somehow i'm not able to solve this simple thing.
Activating by ID in cloth bind or property test with Material ID won't work?

Thanks in advance tyflow fam!