geGetSelSet() not worked on softblock's shape

Hi,

There is a top block layout and a sub-block(softMacro) was placed inside the softMacro, after that, a pin belongs to sub-block was selected in top block layout level, and I tried to use geGetSelSet(), but the return value is nil? Is there any other function that I can use to report selected pin information? 

Many Thanks

Amos