8024f LAG across stack members

I have 2 8024F switches in one stack.  

I want to use interface 1/0/21-24 and 2/0/21-24 to be part of the same port channel. Is this possible? When I try do this, I get the following error. 

"Row Number 23: Error! LAG members do not have same speed, duplex or auto-negotiation settings."

Thanks