Exporting and Importing Sharepoint site

I recently exported a sharepoint site using the following command:-
stsadm.exe -o export -url http://(Site Collection A) -filename C:\Export.cab -includeusersecurity -versions 4

And them imported it under the defaut Sharepoint publishing page at http://localhost using the following command:-

stsadm.exe -o import -url http://localhost/sitecollectionA -filename C:\Export.cab -includeusersecurity

Which worked fine and sure enough a new tab appeared with the imported site collection. Now here's the problem.... I went into the site and from 'Groups and People' I clicked on Members } New to add a new member. The 'Add user' screen appeared and I added the user from AD. In the give permissions section there are two options:
1. Add users to sharepoint group
2. Give users permissions directly
The problem is each group in option one states (NO ACCESS) in brackets (e.g Homesite Members (No Access)) and second option 'give users permissions directly is completely greyed out and not selectable. I noticed i didn't used the 'overwrite' command in the export, would this cause a problem?

Any help will be greatly appreciated