I'm trying to create a point IFeatureClass, but my code doesn't work.

Public Function CreatePointFeatureClass(ByVal featureClassName As String, _
                                         ByVal featureWorkspace As IFeatureWorkspace) As IFeatureClass

    ' Instantiate a feature class description to get the required fields.
    Dim fcDescription As IFeatureClassDescription = New FeatureClassDescriptionClass()
    Dim ocDescription As IObjectClassDescription = CType(fcDescription, IObjectClassDescription)

    Dim fields As IFields = New FieldsClass
    Dim fieldsEdit As IFieldsEdit = CType(fields, IFieldsEdit)
    Dim fieldUserDefined As IField = New FieldClass
    Dim fieldEdit As IFieldEdit = CType(fieldUserDefined, IFieldEdit)

    ' Set up geometry definition for the Shape field.
    ' You do not have to set the spatial reference, as it is inherited from the feature dataset.
    Dim geometryDef As IGeometryDef = New GeometryDefClass
    Dim geometryDefEdit As IGeometryDefEdit = CType(geometryDef, IGeometryDefEdit)

    ' By setting the grid size to 0, you are allowing ArcGIS to determine the appropriate grid sizes for the feature class. 
    ' If in a personal geodatabase, the grid size is 1,000. If in a file or ArcSDE geodatabase, the grid size
    ' is based on the initial loading or inserting of features.
    geometryDefEdit.GeometryType_2 = ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPoint

    ' Set standard field properties.
    fieldEdit.Name_2 = "SHAPE"
    fieldEdit.Type_2 = esriFieldType.esriFieldTypeGeometry
    fieldEdit.GeometryDef_2 = geometryDefEdit
    fieldEdit.IsNullable_2 = True
    fieldEdit.Required_2 = True
    fieldsEdit.AddField(fieldUserDefined)


    ' Add a X Double field to the required fields.
    Dim field1 As IField = New FieldClass()
    Dim fieldEdit1 As IFieldEdit = CType(field1, IFieldEdit)
    fieldEdit1.Name_2 = "X"
    fieldEdit1.Type_2 = esriFieldType.esriFieldTypeDouble
    fieldsEdit.AddField(field1)

    ' Add a Y Double field to the required fields.
    Dim field2 As IField = New FieldClass()
    Dim fieldEdit2 As IFieldEdit = CType(field2, IFieldEdit)
    fieldEdit2.Name_2 = "Y"
    fieldEdit2.Type_2 = esriFieldType.esriFieldTypeDouble
    fieldsEdit.AddField(field2)

    ' Add a Elevation Double field to the required fields.
    Dim field3 As IField = New FieldClass()
    Dim fieldEdit3 As IFieldEdit = CType(field3, IFieldEdit)
    fieldEdit3.Name_2 = "Elevation"
    fieldEdit3.Type_2 = esriFieldType.esriFieldTypeDouble
    fieldsEdit.AddField(field3)




    ' Use IFieldChecker to create a validated fields collection.
    Dim fieldChecker As IFieldChecker = New FieldCheckerClass()
    Dim enumFieldError As IEnumFieldError = Nothing
    Dim validatedFields As IFields = Nothing
    fieldChecker.ValidateWorkspace = CType(featureWorkspace, IWorkspace)
    fieldChecker.Validate(fields, enumFieldError, validatedFields)

    ' The enumFieldError enumerator can be inspected at this point to determine
    ' which fields were modified during validation.
    ' Create the feature class.
    Dim featureClass As IFeatureClass = featureWorkspace.CreateFeatureClass(featureClassName, validatedFields, _
                                    ocDescription.InstanceCLSID, ocDescription.ClassExtensionCLSID, esriFeatureType.esriFTSimple, _
                                    "SHAPE", "")

    Return featureClass

End Function