Removing Thing from Network then use IsInNetwork() on this removed Thing, return true.

Hi,

I tried to remove a Thing from Network using code below.

Networks["NetworkTest"].RemoveFromNetwork({
    name: toolName /* STRING */
});

Then I used IsInNetwork() on this removed Thing, however it returns true.

var result = Networks["NetworkTest"].IsInNetwork({ 
              name: toolName
             });

I took a look under the Network Hierarchy tab. Apparently this Thing no longer exists in Network. Not know how to solve this issue. Hope anyone can help. Thanks a lot.