Message waiting indictator

Hi,

I am having trouble with the MWI staying on for more than 1 minute,

I have tried several setting changes.

We use 2Talk as a provider and the message will be received and show up for up to a minute then the light will stop flashing and the mail envelope will disappear.

Am I missing a setting? MWI enabled, and subscription set at 3600.

Thanks is advance
Darrin