Update Data In SQL Server Express 2008 Using VB 2010

Here is the code snippet

objCommand.CommandText = "UPDATE tblCustomers SET weight= @weight, height= @height WHERE id=@id "

What i want to do is the following:

I have a form and i want,by clicking the appropriate button, to update the height and weight values which have the specified primary key 'id'.

The primary key 'id' is of type IDENTITY.The problem is that the above code does not work. It says Must declare the scalar variable "@id".