Probem with Invoice

When viewing an invoice (via the “print invoice” button either as a customer or in admin) the invoice seems fine, but when you view the invoice vie the “print invoice (PDF)” (again either as a customer or from admin) the company logo shows on a black background.

The image used is a transparent png.

Can anyone offer any suggestion as to what may be going on here?



Following the previous post …

I just changed the image to a gif version of the same and the problem went away.

But still would like to have a solution to the original problem. Should it not work with all image formats?