关于查找字符的问题

Public Sub findstr(rtb As RichTextBox)
Dim l1, l2 As Long
If Form1.findstr <> "" Then
SendMessageByRef rtb.hwnd, EM_GETSEL, l1, l2
If rtb.Find(Form1.findstr, l2) = -1 Then
l2 = 0
If rtb.Find(Form1.findstr, l2) = -1 Then
MsgBox "没有找到", vbOKOnly, ""
End If
End If
End If
End Sub
Dim strFind As String
Property Get findstr() As String
findstr = strFind
End Property
Property Let findstr(sFind As String)
strFind = sFind
End Property

运行时,提示发现二义性的名称:findstr
这段是在FORM1的通用下的代码
也是按照书上说的做的,但是我不能很清晰的理解这段代码的意思
并且为什么出现这样的错误提示?
请大虾给出指导性的意见,小弟跪求