Table Name As An Input Parameter To A Procedure

Hi
I have this procedure it is creating the proc but when I execute it gives error
Msg 137, Level 15, State 1, Line 1
Must declare the scalar variable "@ID".
Msg 137, Level 15, State 1, Line 1
Must declare the scalar variable "@nextCode".

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE PROCEDURE [dbo].[GetNextAction]

(
@Code char(10),
@Track varchar(30)

)
AS
BEGIN

SET NOCOUNT ON;
Declare @ID int;
DECLARE @SQL1 VARCHAR(2000)
SET @SQL1='Select @ID = Sequence from'+' '+ @Track+ ' where Code=@Code'
EXEC(@SQL1);
Declare @nextCode varchar;
DECLARE @SQL2 VARCHAR(2000)
SET @SQL2 ='Select @nextCode= Code from '+' '+ @Track+ ' where sequence =(@ID+1)'
EXEC(@SQL2);
Declare @NextAction varchar(30);
Select @NextAction= nextAction from [dbo].[CaseStage] where Code=@nextCode;
Select @NextAction;


END
GO
Can someone correct me here
Thanks