solder mask for card-edge connector

[FredBl]

I have created a special card-edge connector using SMT and want to leave the board inbetween the pins free from the solder mask.

I have tried this with the keep-in/out area, but that will not work or I am doing something wrong.

How can I create a free area in the solder mask layer?

[TMP]

In the Design toolbox click on the Layer tab, make solder mask your active layer.  Select Place-->shape, whatever you shape you place will be expose