We have Freeview on both TVs (on the main TV it is built in to the TV, the other is a seperate box ).
We get the display in the top right of the screen that says "press red button" for the interactive but nothing happens when we press it !?
We weren't getting anything when pressing the red button either. But yesterday i did a scan for new channels (Freeview this is) and it picked up a new one which is the channel 4 interactive channel. Now when we press red we go to live BB! Hope this helps you.