SQL Server :: Incorrect Syntax Near The Keyword "with" - If Statement Is A Common Table Expression

i am writing storedprocedure for creating salary table ,but getting error while executing sp.

USE [Crystal.HRM]
GO
/****** Object: StoredProcedure [dbo].[Hrm_Salary] Script Date: 01/19/2011 13:11:02 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE PROCEDURE [dbo].[Hrm_Salary](
@Pay_Basic char(1),
@Pay_Hra char(1)
)
AS
BEGIN
declare @fields nvarchar(max)
set @fields='Hrm_Emp_Id [int] not null'
if(@Pay_Basic='Y')
Begin
set @fields=@fields+', Pay_Basic [int] NOT NULL CONSTRAINT [DF_Hrm_Emp_Salary_Pay_Basic] DEFAULT ((0)),'
end
if(@Pay_Hra='Y')
Begin
set @fields=@fields+', Pay_Hra [smallint] NOT NULL CONSTRAINT [DF_Hrm_Emp_Salary_Pay_Hra] DEFAULT ((0)),'
End
set @fields=substring(@fields,0,len(@fields)-2)
declare @sql nvarchar(max)
set @sql='CREATE TABLE [dbo].[Salary]('+
@fields+'
CONSTRAINT [PK_Payroll] PRIMARY KEY CLUSTERED
(
[Pay_Emp_Id] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
GO
USE [Crystal.HRM]
GO
ALTER TABLE [dbo].[Hrm_Emp_Salary] WITH CHECK ADD CONSTRAINT [FK_Hrm_Emp_Salary_Hrm_Emp_Tbl] FOREIGN KEY([Pay_Emp_Id])
REFERENCES [dbo].[Hrm_Emp_Tbl] ([Emp_Id])'
exec sp_ExecuteSql @sql
END