这句在Crystal Report里的Crystal Syntax有什么错呢？老提示出错。

[miaomiaoga]

Local numberVar nTotal_Price := {Company_Invoice_View_Item.Total_Price};
if not isnull(nTotal_Price) then //<==出错，提示"A field is required here"
"合计: " & nTotal_Price
else
"合计: " & {#RTotal1}