The image files contained in WebGrid may loaded from two locations, they are:

• specified folder/location
  When Folder property of ImageSettings is set to a specified folder/location, the image files contained in WebGrid will be loaded from the specified location. By default, the images folder is CommonLibrary/Images.
  To know whether an image is loaded from physical location, you can do the following:
  1. Open the page which containing WebGrid in browser.
  2. View the src property of the img tag from the specified image using web developer tools. You can press F12 in IE 9 to open the built in developer tools or press Ctrl+Shift+I in Mozilla Firefox 10.x.x browser to open the built in Inspect or by using other third party developer tool.
  3. The src of the <img> tag should look like following: <img src=”[ImageFolder]/wg_filter.gif” />
• http handler
  When SmartWebResources is enabled and the mode is set to Auto; scripts, images, and other general client resources should be loaded from http handler. If your page is working fine and the controls are functioning properly, this indicates that SmartWebResources has been enabled and running properly.
  To know whether an image is loaded from physical location, you can do the following:
  1. Open the page which containing WebGrid in browser.
  2. View the src property of the img tag from the specified image using web developer tools. You can press F12 in IE 9 to open the built in developer tools or press Ctrl+Shift+I in Mozilla Firefox 10.x.x browser to open the built in Inspect or by using other third party developer tool.
  3. The src of the <img> tag should look like following: <img src=”[AppName]/ISRes.axd?G/wg_filter.gif” />

If the image is loaded from physical folder and still not reflected on grid, please ensure that the image url has pointed to the correct one. The default image for the funnel-like filter icon of WebGrid is wg_filter.gif. Based on your information, that you have added a new image with the same name under the same location, please try to ensure that the new image has .gif file extension as well.

If the image is loaded from http handler, I’d like to suggest you to set the Folder and FilterImage property of WebGrid’s ImageSettings.

Hope this helps.