请教高手，vba如何判断单元格公式错误

比如，sheet1，a=date，b列单元格里的公式错误时，执行宏“aaw”，否则继续执行该单元格公式，这个语句如何写？

sheet1.[b1].formula = "=.................."
if not  intersect(sheet1.[b1], sheet1.SpecialCells(xlCellTypeFormulas, 16)) is nothing then
sheet1.[b1], clear
run "aaw"
end if

你好！我把附件上传，请你帮我看看如何改？条件：sheet1.[a]=date，检测到该行b单元格公式错误时，执行宏“aaw”，否则，仍然执行原公式

我测试错误！
Sub aa()
Dim i As Integer
For i = 1 To 31
With Sheet1
If .Range("a" & i) = Date Then
Sheet1.[b1:b31].Formula = "=SUM(RC[1]:RC[8])"
If Not Intersect(.Range("b" & i), Sheet1.SpecialCells(xlCellTypeFormulas, 16)) Is Nothing Then
.Range ("b" & i), Clear
Run "aaw"
End If
End With
Next i
End Sub