Hi Jill, I was having this problem too, but I found that using some electrode gel instead of water provides more consistent performance. I bought some off Amazon (http://www.amazon.com/Spectra-Electrode-Parker-Labs-250GM/dp/B0002CA8RQ/) and now my Polar strap is a lot better.
The past week I've had some strange things going on with my HR monitor. I think it's the Polar strap malfunctioning. It has my HR all over the place and it doesn't connect well to the Bioforce app. I changed the battery and still it's acting strange. Has anyone else seen this happen and is there a solution other than sending it back to Polar for a replacement?