How to find average in pivot - sql-server

Question

I have Two Table in sql server 2008
TABLE [tblTagDescription](
[ID] [bigint] IDENTITY(1,1) NOT NULL,
[TopicID] [int] NULL,
[TagID] [int] NULL,
[FullTag] [nvarchar](50) NULL,
[ValDecimal] [nvarchar](50) NULL,
[ValBinary] [nvarchar](50) NULL,
[GroupName] [nvarchar](50) NULL,
[ReportTag] [nvarchar](50) NULL
)
And
TABLE [tblDataLog](
[ID] [bigint] IDENTITY(1,1) NOT NULL,
[TagDescID] [bigint] NULL,
[Value] [decimal](18, 2) NULL,
[Date] [datetime] NULL,
)
Here there might be same Group for multiple "Id" of tblDescription and "TagDescID" of tblDataLog.
Here 'Group1' has 10 ID as from 1 to 10. and there might be multiple record for these ID (from 1 to 10) in tbldatalog. I want these ID from 1 to as columns. I want Average of these ID (From 1 to 10).
For this I used pivot:
Declare #COls nvarchar(max)
Declare #SQL nvarchar(max)
DECLARE #COlsID NVARCHAR(MAX) = ''
DECLARE #COlsAlias NVARCHAR(MAX) = ''
IF OBJECT_ID('tempdb..##MYTABLE') IS NOT NULL DROP TABLE ##MYTABLE
IF OBJECT_ID('tempdb..#tt') IS NOT NULL DROP TABLE #tt
IF(#Group='A')
BEGIN
Select #COls=COALESCE(#Cols + '],[','') + z.ReportTag From
(Select Distinct T.ID, ReportTag From tblTagDescription T
Where isnull(ReportTag,'')<>'' AND T.GroupName=#Group Group BY T.ID,T.ReportTag --order by T.ID
)z
END
ELSE
BEGIN
SELECT
#COlsID = #ColsID + ',' + z.TagDescID,
#COlsAlias = #COlsAlias + ',' + z.TagDescID + ' AS ' + z.ReportTag
FROM
(select TagDescID,ReportTag from(SELECT DISTINCT TOP 50 QUOTENAME(CONVERT(NVARCHAR(25),
tblDataLog.TagDescID )) TagDescID,TagdescID TID,
QUOTENAME(tblTagDescription.ReportTag) ReportTag
FROM tblDataLog
INNER JOIN tblTagDescription ON tblDataLog.TagDescID = tblTagDescription.ID
where tblTagDescription.GroupName=#Group
ORDER BY tblDataLog.TagDescID )s
) z
END
SET #COlsID= STUFF(#COlsID,1,1,'')
SET #COlsAlias= STUFF(#COlsAlias,1,1,'')
SET #SQL='select [DATE],SHIFT, ' + #COlsAlias + ' into ##MYTABLE from ( select [Date], AVG(Value), TagDescID,
(CASE
WHEN ((DATEPART(hour,[DATE]))>6 and (DATEPART(hour,[DATE]))<14) THEN ''A''
WHEN ((DATEPART(hour,[DATE]))>=14 and (DATEPART(hour,[DATE]))<22) THEN ''B''
WHEN ((DATEPART(hour,[DATE]))>=22 or (DATEPART(hour,[DATE]))<6) THEN ''C''
END )AS SHIFT
from tblDataLog Group by [Date],[TagDescID] )d pivot(max(Value) for TagDescID in (' + #COlsID + ')) piv;'
EXEC (#SQL)
select * from ##MYTABLE
But the above query is giving error as :
Msg 8155, Level 16, State 2, Line 8
No column name was specified for column 2 of 'd'.
Msg 207, Level 16, State 1, Line 8
Invalid column name 'Value'.
Msg 208, Level 16, State 0, Procedure Select_DataViewer, Line 58
Invalid object name '##MYTABLE'.
How to solve this?