Inventory reults not being sent from machine

Hi we are running notifcation server 7.1.

Getting an increase of client PC's that run their inventories but then are not sending the results back to the server.

I have looked within the jobs and tasks but cannot see how to force the send.

Has anyone else encountered this error before and can anyone suggest a solution?

I do not want to have to reinstall the agent if I can help it.

Thanks in advance