This will sound weird....but try licking the band. Just a good old dribble across the bit that's over your heart. Couldn't say exactly how HRMs work, but they need a really good contact with your skin. Dribble does this.
Decided I'd quite like to try out some compression tights, see what all the fuss is about. Came across these More Mile Compression Tights which are an awful lot cheaper than others such as 2XU or Skins. Anyone got any experience of these? Are they cheaper for a good reason, ie they're crap ?