Error message - please help

Hi there

My husband multiboxes with five toons, which is allowed but whenever I try to play with him on one toon, he gets warning about multiboxing as well as gets kicked. Then our health and mana take a beating... Just wondering how we can rectify this as we are following all the rules.
To clarify He is on his own PC with 5 clients running and I am on a SEPARATE PC with my 1 client running. When I sign on, he gets error messages saying
Excessive multiboxing detected

Thanks again for your help

Multiboxing limit is pretty much equivalent of "up to 5 accounts connected per household". You are trying it with 6 basically, and get the effect of system detecting 6 accounts connected.