With CSS the only images that you can load into a table cell are background images, and a background image in a table cell will:
1) Tile if the image is smaller than the table cell that it is in.
2) Get cut off if it is larger than the table cell that it is in.
My guess (since you didn't include the html you used for the table your logo is in) is that the cell that contains you logo is getting "crushed" and that's why you can't see it.
What I did for my site was to create a transparent gif file with the same dimensions as my logo, set the transparent gif as the foreground image in the cell, and then use CSS to define a background image for the same cell. The column next to my logo is set to a width of 100% so that the cell that has the transparent gif is no larger than the transparent gif itself. Then I made different logos for each style sheet on my site and added a "logo" class to all of my style sheets to load the appropriate background image.
View source on my site to see what I mean
Edited cause I need a lot more coffee...
