Well there's also:
But that's only supposed to be for older IE (version 5 or less). Just to be on the safe side, make that:
ma_tab='<ta'+'ble align="'+effectalign+'" border="0" style="background-color:#000000">';
And that might be a good idea with the line you deleted, bring it back and make it:
ma_tab='<ta'+'ble align="'+effectalign+'" border="0" style="background-color:transparent">';
But none of that should matter in today's browsers. It might though if you have conflicting styles elsewhere on or associated with the page. I'm thinking that there's something else about the page you have it on that's causing a background other than the one you want. Other HTML and/or styles of the page could be causing it.
If you want more help, please include a link to the page on your site that contains the problematic code so we can check it out.