sql select statement error

Question

SELECT Date,MIN(VchNo) +'-'+MAX(VchNo) as VchNos--, Form,[VAT %],SUM(TaxableValue) as TaxableValue,SUM(TotalVAT) as TotalVAT,SUM(Total) as Total    

FROM (

SELECT   CONVERT(varchar(10), InvTransactionMaster.TransactionDate, 105) AS Date,  

                      InvTransactionMaster.VoucherPrefix + ' ' + CAST(InvTransactionMaster.VoucherNumber AS varchar) AS VchNo,   

                      InvTransactionMaster.VoucherType + ' ' + InvTransactionMaster.VoucherForm AS Form, InvTransactionDetails.VatPercentage AS [VAT %],   

                      SUM(InvTransactionDetails.NetValue) AS [TaxableValue], SUM(InvTransactionDetails.TotalVatAmount) AS [TotalVAT],   

                      SUM(InvTransactionDetails.NetValue + InvTransactionDetails.TotalVatAmount) AS Total  

FROM         InvTransactionDetails INNER JOIN  

                      InvTransactionMaster ON InvTransactionDetails.InvTransactionMasterID = InvTransactionMaster.InvTransactionMasterID  

WHERE  InvTransactionMaster.IsActive =1   

   AND InvTransactionMaster.VoucherType ='SI'   

  AND InvTransactionMaster.BranchID=1--@BranchID  

   AND InvTransactionDetails.BranchID=1--@BranchID  

   AND InvTransactionMaster.TransactionDate BETWEEN '2015-02-06' and '2015-02-07'--@FromDate AND @ToDate  

   --AND (@VATPerc=-1 OR InvTransactionDetails.VatPercentage =@VATPerc)  

                        

GROUP BY InvTransactionMaster.TransactionDate,   

                      InvTransactionMaster.VoucherPrefix, InvTransactionMaster.VoucherNumber, InvTransactionMaster.VoucherType, InvTransactionMaster.VoucherForm,   

                      InvTransactionDetails.VatPercentage  

                       ) AAA GROUP BY AAA.Date,AAA.Form,AAA.[VAT %] ORDER BY AAA.Date  


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this is my query ....every thing fine but for a particular date it showing some error ...any body have any idea....i give the all the details....