怎么解决调用sub出现“语句未结束”错误？

Dim n,a
n=Int(InputBox("n"))
a=Split("0 "&InputBox("a()"))
For i=1 To n
    For j=i+1 To n
        If a(j)<a(i) Then
            swap a(j) a(i)
        End If
    Next
Next
MsgBox(Join(a))
Sub swap(byRef x,byRef y)
    Dim z
    z=x
    x=y
    y=z
End Sub

这是我的代码
下面是错误信息

 Sub swap(ByRef x, ByRef y)
        Dim z
        z = x
        x = y
        y = z
    End Sub
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Dim n, a
        n = Int(InputBox("n"))
        a = Split("0 " & InputBox("a()"))
        For i = 1 To n
            For j = i + 1 To n
                If a(j) < a(i) Then
                    swap(a(j), a(i))
                End If
            Next
        Next
        MsgBox(Join(a))


    End Sub

改成这样就行了呀