Redundant Switch Connection

Hi,

I have several Dell 2724 switches that I would like to set up redundantly.

I have joined two 2724s with a trunk. I would now like to connect the access switch with one connection to each of the two trunked switchs. One cable in switch1 everything works. Put second cable in switch2 and all breaks loose.

Switch1=Switch2 (LAG)

\       /

Switch3

Can someone tell me if this works and how?

Thanks