[5分]if语句判断出错

Public Sub btndel()
'    If MsgBox("您确认要删除吗？", vbYesNo + vbInformation, Forms!usysfrmlogim.Caption) = vbYes Then
'        DoCmd.Echo False
'        Call acchelp_deletefldstrrow("tblcodeyg", "ygid", selectstr)
'        Forms!usysfrmmain!frmChild.SourceObject = "frmyg_child"
'        DoCmd.Echo True
'    End If
End Sub

上面这段代码执行中出错了。没有显示代码出错，而是删除不掉数据；修改如下代码后就可以了。  结论：“if 语句的判断没有判断到，直接跳到出错语句去了” 请详细解释哪个位置出错？
Public Sub btndel()
If MsgBox("您确认要删除吗？", vbYesNo + vbExclamation, "提示") = vbYes Then
Call acchelp_DeleteFldstrRow("tblcodeyg", "ygid", selectstr)
        Forms!usysfrmmain!frmChild.SourceObject = "frmyg_child"
        DoCmd.Echo True
End If
end sub