AF project wont show preview whenI open it

Hi,

I created an after effects project on my work computer but whn I try and open it on my home computer all I get is a grey screen where the preview should be?

I've copied across all my assets and folders onto my hard_drive also so it isn't a missing file issue.

This has never been a problem before....I've attached a .jpg below of what I see when I open the file. The timeline is all correct but no images are being displayed...

Please help?

James