404 error when loading a image

I used ext js framework to build my web site. but there is alway a image that cannot be found, that means always return a 404 error. the image link is "http://localhost/undefined". I checked the HTML,开发者_StackOverflow and did not found any tag that its link is like this. I wonder if I miss some steps when using the ext js framework, do any one know this issues?

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have you try define the Ext blank image ??

try this :

Ext.onReady(function(){
   Ext.BLANK_IMAGE_URL = '../extjs/resources/images/default/s.gif';
   .....
   //your code
   .......
});

if still not solve.. try update your question with your current code..