语法不正确的SSRS IF语句

Question

我是SSRS的新手，发现语法非常困难，还有糟糕的表达式文本框，很难看出我在哪里犯了错误。

我想做IFF(First(Fields！TaxNumber.Value，"InvoiceHeader"(=null，然后只打印IS02Chars.Value，否则同时打印IS02Chars和TaxNumber.Value。

=IFF (First(Fields!TaxNumber.Value, "InvoiceHeader") = null ,
": " & First(Fields!ISO2Chars.Value, "InvoiceHeader"), 
": " & First(Fields!ISO2Chars.Value, "InvoiceHeader") & First(Fields!TaxNumber.Value, "InvoiceHeader"))

我看不出我的语法与IIF(Fields!ExitReason.Value = 7, 1, 0)有什么不同

Answer 1

=IIF(IsNothing(First(Fields!TaxNumber.Value, "InvoiceHeader")), ": "
& First(Fields!ISO2Chars.Value, "InvoiceHeader") , ": " &
First(Fields!ISO2Chars.Value, "InvoiceHeader") &
First(Fields!TaxNumber.Value, "InvoiceHeader" ) )