pyqgis - Labelling line layer using QgsPalLayerSettings() QGIS failed

I'm trying to set label on polygon and line layer using PyQGIS. Setting label on polygon layer succeed, but fails on line layer.

Here my script :

        #Set polygon layer
        palyr = QgsPalLayerSettings()
        palyr.readFromLayer(layer_base)
        palyr.enabled = True  # this works
        palyr.fieldName = 'no_urut'  # this works
        palyr.fontSizeInMapUnits = False

        palyr.textFont.setPointSize(6)  # results in 4 - seems to be integer only
        palyr.textColor = QColor(0, 0, 0)  # this works
        palyr.writeToLayer(layer_base)

        #set label line layer
        palyr3 = QgsPalLayerSettings()
        palyr3.readFromLayer(layer_jalan)
        palyr3.enabled = True  # this works
        palyr3.fieldName = 'nama_jalan'  # this works
        palyr3.fontSizeInMapUnits = False

        palyr3.textFont.setPointSize(11)  # results in 4 - seems to be integer only
        palyr3.textColor = QColor(0, 0, 255)  # this works
        palyr3.placementFlags = QgsPalLayerSettings.AboveLine
        palyr3.writeToLayer(layer_jalan)

Any ideas ?, btw when I load it and check on the layer properties, the label has been set according to the properties in the script above and, when I push the apply button on this properties window, the label appears on the canvas.

Answer

There is probably a mistake in the syntax for QgsPalLayerSettings().

You may try to write this:

palyr3.placement = QgsPalLayerSettings.AboveLine

instead of:

palyr3.placementFlags = QgsPalLayerSettings.AboveLine

Furthermore, you should add this line at the end of the code:

iface.legendInterface().refreshLayerSymbology(layer_base)

With these edits, you should use this code (it worked for me):

palyr3 = QgsPalLayerSettings()
palyr3.readFromLayer(layer_jalan)

palyr3.enabled = True  # this works
palyr3.fieldName = 'nama_jalan'  # this works
palyr3.fontSizeInMapUnits = False
palyr3.textFont.setPointSize(11)  # results in 4 - seems to be integer only
palyr3.textColor = QColor(0, 0, 255)  # this works
palyr3.placement = QgsPalLayerSettings.AboveLine
palyr3.writeToLayer(layer_jalan)
iface.legendInterface().refreshLayerSymbology(layer_jalan)