错在哪里?一个函数

Public Function RecordSave(Frm As Form)
    On Error GoTo Err_RecordSave
    Dim ctl As Access.control
    Set cnn = CurrentProject.Connection
    For Each ctl In Frm.Controls                '循坏检查文本、组合框、列值框控件的"标记"属性，如果值是"BT"，则检查是否填写
        If ctl.ControlType = acTextBox Or ctl.ControlType = acComboBox Or ctl.ControlType = acListBox Then
            If ctl.Tag = "BT" And IsNull(ctl.Value) = True Then
                MsgBox "数据输入不完整, " & ctl.Name & " 是必填内容!", , "系统提示"
                ctl.SetFocus
                RecordSave = False
                Exit Function
            End If
        End If
    Next ctl
 
Exit_RecordSave:
    Exit Function
Err_RecordSave:
End Function
帮我看一下啊，一个函授
错在哪里