Hi, there are a few posts on this issue, but:
1. Have you moistened behind the belt where it rests on your chest? Often it will not get a connection for heart rate if you don't (not sure if this is the issue or not)
2. Follow directions at:
a.
How_to_install_new_battery-Suunto_Tranmitter_Belt
b.
http://suunto.goodmood.net/SuuntoVid...moving_battery)
c.
http://suunto.goodmood.net/SuuntoVid...moving_battery)