Desperately need help with images!

I upload all of my products via csv file. This is how I control pricing, special offers, everything!
I currently have over 400 products loaded and since this is a new shop...(yet to be launched)...I am uploading updates on a daily basis.

My problem is this:
Every time I do a new upload, my images no longer show up. Names have not changed, locations have not changed...nothing has changed, but the images no longer show up. Having 400+ products and growing, I do not have time to go in and reload the photos every time I do an upload...which is something else I don't understand. Why am I having to go back to my computer to reattach the image when it is right there in Hikashop? Is this creating duplicate images and wasting my disk space? I should be able to go to my upload folder to attach the images.

This may very well be due to my lack of understanding, but I have searched every where I can think of to see if I am doing something wrong.

Any help you folks can offer will be greatly appreciated.

btw:
Hikashop 1.5.5
Joomla 1.7

Thanks

You were exactly right. Some of my product image names did not match exactly and some of them did not transfer at all when I uploaded via FTP.

Thanks for the help.