Table rows disappear

I want to give every other row in a table a background color or background image, to optimize the readability of the table. But when I set the attributes for a row and save the page or simply switch between code mode and wysiwyg, the row has disappeared.

Only the very first row seems to accept attributes, all of the other rows that I try to assign a background color to get eaten.

The problem doesn’t seem to be theme-related, so I think it’s a bug in WordPress itself. Any ideas for a workaround? Thanks!