Usercontrol propery

I'm trying to add a Public WriteOnly Property SetID to my Usercontrol. And when I try set the value from my page I get this error:

Property access must assign to the property or use its value.myUC.SetID = 1 Public WriteOnly Property SetUrl(ByVal _URL As String) As String
Set(ByVal value As String)
URL = _URL
End Set
End Property

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