至少一个参数没有被指定值，是怎么回事

Private Sub Command2_Click()

 
    Dim Rs As ADODB.Recordset
    Dim Sql As String
    Dim MsgTxt As String
    Dim NR1 As String
    Dim RQ1 As String
   
    If List3.ListIndex = -1 Then Exit Sub

RQ1 = List1.List(List3.ListIndex)

NR1 = List2.List(List3.ListIndex)

 Sql = "delete * from MYBOOK where RQ=RQ1"
                Set Rs = ExecuteSQL(Sql, MsgTxt)
               
                If InStr(MsgTxt, "错误") Then
                    MsgBox MsgTxt, vbCritical, "错误提示"
                    Exit Sub
                End If
               Text1.Text = ""
              
                i = List3.ListIndex
                  List1.RemoveItem i
                  List2.RemoveItem i
                  List3.RemoveItem i
                    
End Sub