F5 LTM Connected to Cisco FEX

Has anyone configured F5 LTM's to connect to Cisco FEX [fabric extenders]. We have 4 10G ports on our FEX that we are trying to bundle. Individually the interfaces come up, but as soon as we bundle them, the connection goes down.

 

Any config samples/best practices for connecting LTM's to FEX's.?

 

Thanks.