I have place two div one after another. All these div have position relative property. When I placing another div with position absolute property its goes under the second div. while z-index property also not working in this manner.
You have some typos in your code (missing "): e.g.
<div class="block2[COLOR="Red"]"[/COLOR]>
All the same, IE7 and under is a bit screwy with z-index. If you need to use “block1” more than once, it might be better to wrap the first one in a special container with a higher z-index than “block1”. E.g.