Validation of viewstate MAC failed

各位仁兄：
        小弟开发的mobile web应用程序在IE中测试一切正常，可在Pocket IE 中测试时候，页面不能刷新，出现以下错误。
        Validation of viewstate MAC failed. If this application is hosted by a Web farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.
        我在网上查询，看到一个解决方法如下修改了web。config，可依然出同样的错误，我该怎么办？
        Solution: Add the following setting to the Web.config file on either the computer hosting the Federation Service, Federation Service Proxy, or Web Service Agent that will be farmed using a text editor:

<system.web>

<machineKey>
<machineKey validationKey="specify key for the appropriate algorithm" decryptionKey="specify key" validation="SHA1|MD5|3DES"/>