Normally, when import doesn't let you select a photo and it greys out the photo ... it means you have already imported the photo into Lightroom, and then there is no reason to import it again. You simply go to the Library Module, find the photo, and edit it or export it or whatever.
this is the problem i haven't already imported the photo as it is straight from the camera (on the memory card)
I have been using two cameras so maybe its got confused?
I doubt that this is the problem.
Is the photo greyed out in the Import dialog box?
Can you show us a screen capture of the Import dialog box when you are unable to import?