Running apps connecting to GPS blocked by case/arm-band

[jwckauman]

I have a new arm-band for my Nokia 920. However when it's in the band, it can't seem to connect to the GPS. I have a running app that tells me how far I have run. When it's out of the arm-band, it works fine. When its in the arm-band, it can't find my location. Does anyone know what might be going on here? How I might fix it?