asp.net Crystal report icon does not show the solution

ASP tutorials Solution for the. NET Crystal Report icon not shown
Sometimes in the Crystal report to add a pie or bar chart, the page display fork, that is, the picture has no output, the solution is as follows:

Add the following node to the Web.config

<system.web>

The ASP.net tutorial Web application web.config files store global settings, such as database tutorial connection information, assembly references, and error handling. This file is written in XML format, and its root element must always be <configuration>. This is an advanced configuration and is not required.

The following elements are unique to the Crystal Reports and can be added to the Web.config file.

Crystalimagehandler
The Crystalimagehandler element displays all the dynamic images in the Crystalreportviewer control. This setting configures the ASP.net worker process so that requests made to crystalimagehandler.aspx are redirected to an internal-only image handler class. If there is no Crystalimagehandler setting in the Web.config file, the image on the Web site will not appear. When you add a Crystalreportviewer control to a Web site, this element is automatically added to the Web.config file.

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<system.web>
<add verb= "Get" path= "crystalimagehandler.aspx type=" Crystaldecisions.web.crystalimagehandler, Crystaldecisions.web, version=10.5.3700.0, culture=neutral, publickeytoken=692fbea5521e1304 "/>
</system.web>

Crystalimagecleaner
The Crystalimagecleaner process automatically deletes the dynamically generated images that the Crystalreportviewer control renders. This setting allows you to set the minimum time interval for scanning image directories and files before deleting files. When you add a Crystalreportviewer control to a Web site, this element is automatically added to the Web.config file. This element corresponds to the Crystalimagecleaner class.

Crystalimagecleaner-sleep the time (in milliseconds) that the image cleaner sleeps before it scans and cleans the image files in the dynamic image directory.
Crystalimagecleaner-age the minimum time, in milliseconds, that an initialization file exists before it is deleted.
Crystalimagecleaner-autostart controls the Crystalimagecleaner process. The image cleaner cleans up temporary images that are created when you view reports whose values are set to true.
Attention
Only one image cleaner can be started in a single asp.net worker process.

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<appsettings>
<add key= "Crystalimagecleaner-autostart" value= "true"/>
<add key= "Crystalimagecleaner-sleep" value= "60000"/>
<add key= "Crystalimagecleaner-age" value= "120000"/>
</appsettings>

Look more in detail

Http://msdn.microsoft.com/zh-cn/library/ms227537.aspx