TF31003. Either you have not entered the necessary credentials or your user account does not have permission to connect to the Team Foundation server.

Scenario

Trying to connect to TFS 2010 using VS 2008 Team Explorer where TFS is on a different domain than the current logged in Domain.

Solution

Make sure the Server URL is the full URL along with the Team Project Collection Name. If you don't provide the Project Collection Name in the URL then you will get the above error.
http://[server name]:[port name]/tfs/[project collection name]

Also make sure to include the domain beside the user name when you are asked for credentials as the TFS server is on a different domain.
User name: domain name\username

RDL and RDLC

RDL - RDL stands for Report Definition Language

RDLC - Report Definition Language Client-side processing

RDL files are created by the SQL Server 2008 version of Report Designer. RDLC files are created by the Visual Studio 2008 version of Report Designer.

RDL and RDLC formats have the same XML schema. However, in RDLC files, some values (such as query text) are allowed to be empty, which means that they are not immediately ready to be published to a Report Server. The missing values can be entered by opening the RDLC file using the SQL Server 2008 version of Report Designer. (You have to rename .rdlc to .rdl first.)