Error: Failed to retrieve the data for this request. While choosing data source.

Failed to Retrieve the data for this request.
[C:\Windows\assembly\GAC_MSIL\Microsoft.SqlServer.Management.Sdk.Sfc\10.0.0.0_89845dcd8080cc91\Microsoft.SqlServer.Management.Sdk.Sfc.dll] The signature is incorrect.

Hi,     I am getting above error while I am choosing the datasource. Steps I followed is: for a Dropdown Control, Choose Datasource->New datasource->Sql Server->Choose Data connection->new Connection then Choosen the Server then took sql Authentication,  entered Username, password,  Picked the database from the dropdown. After I click OK, I get this error. Kindly Suggest.