Problem: You make updates to your BDC Model in Visual Studio 2010 and then deploy those updates to a SharePoint farm. However, the updates don’t appear, or you see a "Parameter is Missing" error message.
Some examples of model updates that might not always propagate on redeployment are adding the ShowInPicker property to one or more type descriptors in an entity or reordering type descriptors in an entity’s ReadList method so that the column order changes in the target list. The Parameter is Missing error can be caused if you remove a type descriptor from an existing entity and redeploy the model to be used by an existing external list.
Solution: From Central Administration navigate to Application Management, Manage service applications, then select the Business Data Connectivity Service application proxy that hosts your BDC solution.
In the drop-down appearing in the Ribbon’s View tab, select External Content Types. Delete any external content types that were updated in the BDC model, then re-deploy the BDCM from Visual Studio 2010.
See more SharePoint Q&As:
Sharepoint Q&A: How Can I Create an External List When SharePoint Throws an Unspecfied ASP.NET Error?
Sharepoint Q&A: How Can I Create an Action for an External Content Type in SharePoint?
Sharepoint Q&A: How to Make a Type String Type Descriptor a Required Field in the BDC Explorer
Sharepoint Q&A: Data Source Conflict