Error converting data type nvarchar to numeric. in Sql Serve

Question

Error show

Msg 8114, Level 16, State 5, Line 1

Error converting data type nvarchar to numeric.

 

query

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Select ROW_NUMBER() over(ORDER BY DATENAME(MONTH, convert(datetime,Date,105))+'-'+DATENAME(year, convert(datetime,Date,105)) ASC) as ID,

DATENAME(MONTH, convert(datetime,Date,105))+'-'+DATENAME(year, convert(datetime,Date,105)) as Month,

sum(cast(Amount as numeric(18,2))) as Amount,

sum(cast(Addcost as numeric(18,2))) as Addcost ,

sum(cast(Discount as numeric(18,2))) as Discount ,

sum(cast(Tax_Amount as numeric(18,2))) as Tax_Amount,

sum(cast(Total_Amount as numeric(18,2))) as Total_Amount from MainBillForm where Sno=0 group by DATENAME(MONTH, convert(datetime,Date,105))+'-'+DATENAME(year, convert(datetime,Date,105))

ORDER BY DATENAME(MONTH, convert(datetime,Date,105))+'-'+DATENAME(year, convert(datetime,Date,105))