My web page doesn't show on IE9 document mode.
Because I used frameset tag, I thought my web page failed to satisfy HTML5 standard.
But my another page doesn't have any problem, even using same frameset tag.
I started to find why it happened. There is not answer on the net.
Master Google couldn't help me.(Also Bing and Yahoo)
So I quit searching it on the net and started finding the reason my self with developer tool of IE.
2. a bug of Tomcat 5.5 -> changed to 6.0, but it was same.
3. jsp -> quit using jsp, but...
4. 5. 6. ... 100. 101. ...
Finally, I found the reason after 4 days.
The reason was CSS. After I deleted the following line, My web page started working well.
<link href="/css/style.css" rel="stylesheet" type="text/css"/link>