Why this view does not return data for the last three months?

Hi there,

version: SQL SERVER 2008 SP1

DDL:

CREATE TABLE [dbo].[SalePlans](
	[ProductId] [nvarchar](30) NOT NULL,
	[SupplierId] [nvarchar](30) NOT NULL,
	[PeriodType] [tinyint] NOT NULL,
	[SaleDate] [datetime] NOT NULL,
	[Sale] [float] NOT NULL,
	[Origin] [smallint] NULL,
	[Description] [nvarchar](255) NULL,
	[SafetyStock] [float] NULL,
 CONSTRAINT [PK_SalePlan] PRIMARY KEY CLUSTERED
(
	[ProductId] ASC,
	[SupplierId] ASC,
	[PeriodType] ASC,
	[SaleDate] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY]
) ON [PRIMARY]

GO

This is the view:

ALTER view [dbo].[v_SalePlansByMonth]

as

select SupplierID, productid ,dbo.firstdayofmonth(GetDate()) as [Start Date],
	Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM,0,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM,0,GetDate())) THEN Sale ELSE 0 END),0) AS [SalePlanCurrentMonth]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +1,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +1,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_1]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +2,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +2,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_2]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +3,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +3,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_3]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +4,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +4,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_4]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +5,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +5,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_5]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +6,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +6,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_6]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +7,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +7,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_7]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +8,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +8,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_8]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM, +9,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM, +9,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_9]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM,+10,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM,+10,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_10]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM,+11,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM,+11,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_11]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM,+12,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM,+12,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_12]
	,Round(sum(case when SaleDate between dbo.firstdayofmonth(DATEADD(MM,+13,GetDate())) AND  dbo.Lastdayofmonth(DATEADD(MM,+13,GetDate())) THEN Sale ELSE 0 END),0)  AS [SalePlanMonth_13]

from SalePlans
	where PeriodType = 1
group by SupplierId, productid

UDFs:

CREATE FUNCTION [dbo].[firstdayofmonth] (@date1 datetime)
-- Skilar fyrsta degi viku, án tímasetningar
RETURNS datetime  AS

BEGIN

--return dbo.trimtime(@date1 - (DATEPART(D, @date1) - 1))
return DATEADD(mm, DATEDIFF(mm, 0, @date1), 0)

END

GO



--
CREATE FUNCTION [dbo].[lastdayofmonth] (@date1 datetime)
-- Skilar fyrsta degi viku, án tímasetningar
RETURNS datetime  AS

BEGIN
--return dateadd(mm,1,@date1)
return dateadd(dd,-1,dbo.firstdayofmonth(dateadd(mm,1,@date1)))
END


GO

For this current year (having real data in the table) the view does not return data for month 5,6 and 7.

Can you light up this code in some sense?

Thanks a lot,