Sometimes your phone will have trouble finding a GPS signal and you will not be able to take images. If you have bad GPS signal, try to move a bit and get away from tall buildings. If that doesn’t work, restart your phone and see if that helps.
Bad GPS fix—the capture button to the right is disabled
By default the GMS (Google Mobile Services) are disabled in the Android app—this is to encourage people to start taking pictures outside. But enabling GMS might improve your overall GPS fix. To enable GMS, please go into settings, choose the Developer section and enable “Use Google Mobile Services”—this will enable location fix from several sources.