First, "@State" is not the same as "@state".
Next, Businesscombobox.SelectedItem doesn't return what you think it does. It's going to call .ToString on whatever that selected item is, and that may not return the string you want.
Do yourself a favor and move the Businesscombobox.SelectedItem into its own variable and inspect the content in the debugger.
Dim selected As String = Businesscombobox.SelectedItem
command.Parameters.AddWithValue...
Put a breakpoint on the AddWithValue line and run the code. When the debugger stops on this line, you can hover the mouse over
selected
to see the content that you're passing to the Parameter object.