Choose Company in Navision web service 2009 R2

heveen

Hello Guys
Since few days ago, i am getting a really strange error.
I am using Navision 2009 R2.
I have use the example from this link http://blogs.msdn.com/b/nav_developer/archive/2009/07/08/how-to-set-dynamically-the-key-and-sort-order-for-the-pages-using-nav-2009-web-services-feature.aspx
to implement a sort order for page exposed as web services.

It was working perfectly. Sort by Ascending and descending were working really well.

But some days, i do not know what happen. It all went wrong.
It shows me an error. (See the attached image).
I didnot change anything. When i opened my page web service, it show me that error.

Can you help me in figuring out the error.
Thanks
Heveen