Setting up a redudant pair without changing ip network

No, that's why I think we are not setting up the redudant pair right. There is not problem with the health monitors in the Active Unit but in the Standby one it turns into green or red without any reason although the nodes are up :-|

 

 

we have not tried yet to shut down the active unit, but when we switch it to standby, the health monitors turn red for a while, and again it turns sometimes into green and sometimes into red.

 

 

what is the reason of all of this??