Problem connecting to Wifi on Pi2 (16.04)

Hi,
I’ve just installed on Pi2. All worky until I try to log onto wifi using dongle. The desktop recognises both internet services and gives me the password log on box. When I enter password there is a single tone and the box closes but no connection. In the drop-down box the two services have locked pad-locks next to them. I easily connect to these services with all my other devices by adding the password. I have checked that the keyboard settings are not the issue, including when I check the box to see what I am typing.
Any help would be appreciated.