如何编写SSRS报告表达式？

Question

我转换了

If {W40_10Q.TenureType}="Sub Lease" then
{W40_10Q.CurrentYear}*(-1)
Else
{W40_10Q.CurrentYear}

表达

=IIF(Fields!TenureType.Value = Fields!Lease.Value, "Fields!CurrentYear.Value *(-1)" "Fields!CurrentYear.Value")

但它给了我一个错误。我需要从＆＃34; dataset1＆＃34;中获取TenureType，SubLease，Currentyear。