problem with pictures

Hello everybody!
I have the next problem:
I have two pics in my aspx page, but they are rendering not in the right way.

There is a spache between these 2 pics. You can see it.
I want no space between these 2 pics, how can I do it?
I have searched, but margin or padding don't help me, what should I do?


Here is the part of the page with these 2 pics:

<td id="tab1">         <img src="./btn1.jpg"< ...