Cant access new 3TB Passport for mac on Macbook Pro

Just bought ext storage today and connected to M Pro …all working. Set up passport then disconnected.
Now when I plug the unit in the password pop-up comes visible for about 5 secs then disappears and it closes down the ext drive. Havent been able to access the drive.
Any thoughts?

Try installing WD Security. It should allow for the password prompt to remain active as an application unless there’s an issue with the app in question.

Will do, Thanks… I’ve just thought it might be as have OSX 10.6.8 and not newer…