Do you have VM broadband and a V6 box? Or just TV and a TiVo? If you're not sure, check here
I only ask because... the V6 needs two connections to work. Your TV signals are carried on the white coax cable, but the box also needs an internet connection via your VM Superhub. You need to make sure both are connected.
To resolve Error 7400, follow the advice in the link I posted before - including the call to VM C/S if necessary.
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