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 thanks for all the help, my issue is resolved

Please mark it as answer so it will help for other people

As far i am concerned the error means that "It is not allowing remote connections"

So i think the solution is if you are using Express edition

Go to the Configuration Manager and open it.

After openeing there will be two attributes by name SQL Server(Browser),SQL Server

right click on it and click Stop and restart both of the services

Then check the properties part and everything works fine or not

Let me know if this helps you

http://blogs.msdn.com/sql_protocols/archive/2005/10/22/sql-server-2005-connectivity-issue-troubleshoot-part-i.aspx

Have a look at the following KB article, it will take you through the process of allowing remote connections.

How to configure SQL Server 2005 to allow remote conections
http://support.microsoft.com/default.aspx?scid=kb;EN-US;914277

http://blogs.msdn.com/sql_protocols/archive/2007/03/31/named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server.aspx

http://blogs.msdn.com/sql_protocols/archive/2007/05/13/sql-network-interfaces-error-26-error-locating-server-instance-specified.aspx

 http://www.connectionstrings.com/

Connection strings for SQL Server 2005

http://www.connectionstrings.com/sql-server-2005