Thanks Daniel. I did one of the terrible mistake by not checking the module. The module I have used is not supported for stacking according to Dell Support. The Dell Part No. OU691D.
Hi Guys, I got an issue in stacking two 6224 Dell switches together. I have tried to preconfigured the stack module port to stack mode and connect to the standby switch before power up the standby switch. It happen that both the switch is now the Management Switch, meaning there are not connected yet.  The Running stack Mode is always in Ethernet mode eventhough I have configured it into stack mode. And the configured stack mode will change back to ethernet every time after reload every i have enter the copy run start command.  Appreciate if there is any help on this.  
Issue stacking Dell PowerConnect 6224