کار نکردن دستور z-index برای دو div

[PersianSkyTeam]

این کد رو تست کن :

<button id="AdvancedButton1" type="submit" name="box1" value="" style="position:absolute;left:97px;top:218px;width:311px;height:70px;z-index:0;"><div style="text-align:center"><span style="color:#000000;font-family:Arial;font-size:13px">box1</span></div></button>
<button id="AdvancedButton2" type="button" name="" value="" style="position:absolute;left:97px;top:288px;width:311px;height:64px;z-index:1;"><div style="text-align:center"><span style="color:#000000;font-family:Arial;font-size:13px">box2</span></div></button>

</body>