Failed to save modifications to the server. Error returned: 'OLE DB or ODBC error: [DataSource.Error

Hi.

The full error message is:

Failed to save modifications to the server. Error returned: 'OLE DB or ODBC error: [DataSource.Error] Microsoft SQL: Incorrect syntax near the keyword 'union'.. '.

Trying to append two queries. See all queries below. 

Append – Warranty ratios (BIDW)

let

    Source = Table.Combine({#"Installed base - Power and TiLite (BIDW)", #"Warranty ratios (BIDW)"})

in

    Source

Installed base – Power and TiLite (BIDW)

let

    Source = Sql.Databases("SERVER"),

    DATABASE = Source{[Name="DATABASE"]}[Data],

    DW_V_InvoiceDetailsUNION = DATABASE{[Schema="DW",Item="V_InvoiceDetailsUNION"]}[Data],

    #"Removed Other Columns" = Table.SelectColumns(DW_V_InvoiceDetailsUNION,{"WKInvoiceDate", "WKCustomer", "WKProduct", "IsChair", "SerialNumber"}),

    #"Filtered Rows" = Table.SelectRows(#"Removed Other Columns", each ([SerialNumber] <> null and [SerialNumber] <> "" and [SerialNumber] <> "NA") and ([IsChair] = 1)),

    #"Sorted Rows" = Table.Sort(#"Filtered Rows",{{"WKInvoiceDate", Order.Ascending}})

in

    #"Sorted Rows"

Warranty ratios (BIDW)

let

    Source = Sql.Databases("SERVER"),

    DATABASE = Source{[Name="DATABASE"]}[Data],

    DW_V_InvoiceDetailsUNION = DATABASE{[Schema="DW",Item="V_InvoiceDetailsUNION"]}[Data],

    #"Removed Other Columns" = Table.SelectColumns(DW_V_InvoiceDetailsUNION,{"WKInvoiceDate", "WKCompany", "WKCustomer", "WKProduct", "WKOrderCategory", "SerialNumber", "NetAmount", "CostAmount", "OrderQuantity"}),

    #"Filtered Rows1" = Table.SelectRows(#"Removed Other Columns", each ([SerialNumber] <> null and [SerialNumber] <> "" and [SerialNumber] <> "NA") and ([WKOrderCategory] = 6)),

    #"Filtered Rows2" = Table.SelectRows(#"Filtered Rows1", each [WKInvoiceDate] >= #date(2015, 1, 1))

in

    #"Filtered Rows2"