AbleCommerce Shopping Cart Software

Need support assistance with my issue below:

When I click on Checkout Now a message comes up the says "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 algorithm. AutoGenerate can not be used in a cluster."

I tried adding a machine key to the webconfig file and it didn't resolve the issue. At this time the client can't upgrade to the latest version of able commerce.

If you can assist please contact me via email with your availability and fee info@internetframework.com .

Just to be clear this is a paid support request. If you are a ablecommerce expert please email me at info@internetframework.com.

Have you read this WIKI topic, it may be helpful
http://wiki.ablecommerce.com/index.php/ ... ed_problem

I had checked the problem for him earlier and he had a ConstantContact email subscription form on the page which put another set of form tags on the page.