discovery-interface ethernet command for VLT causes switch to be unreachable via mgmt int

I am trying to set up a vlt domain. I have enabled spanning tree on both switches.

spanning-tree mode rstp

I have connected two 100 gig cables between the switches and both are in up state in ports 1/1/27 and 1/1/28. 5224F are the switches, version 10.5.4.X or something close(can't get in right now to verify)

I add the following command on the first switch

vlt-domain 1 

discovery-interface ethernet1/1/27-1/1/28

About 10 seconds after I add the commands above to the second switch I lose access to both switches. The only other cables plugged in are in the mgmt ports and that is how I am accessing via SSH. If i reboot one switch, I can ssh to the other from the rebooted switch but not my laptop which lives on another subnet. Then I reboot the first switch and can get to it from my laptop. The mgmt ports are both plugged into the same cisco 2960 switch. Another dell networking mystery to solve!! Any help is appreciated.