Question on insert image to a table under Mac IE 5.2+

[Cylix]

I need to using javascript to add some rows on a table,
I get the way to add a row with number of column.
However, I get two problem about the task,

var col = document.createElement('td');
col.setAttribute('colSpan',5);
This does not work for Mac IE5.2

The second one is when I append an image element to the cell,
The cell will expand to about 400px with nothing content.
I have also try to just set the innerHTML with a html code like <img
src=...>,
the same result shown.

Any idea to solve the above two problem?
Thank you.