Invalid Node Name for .createOutputNode()

[venator11387]

I'm learning Python in Houdini and I'm just writing up a simple code. Everytime I try to use the .createOutputNode() I keep getting an `invalid node name` error. The operator name of the node I'm trying to create entering is definitely correct as I've checked using the Type Properties, so I'm not sure what's causing this. 

 

The attempted operation failed.

invalid node name

 

Traceback (most recent call last):

  File "voronoi_set_up", line 16, in <module>

  File "C:/PROGRA~1/SIDEEF~1/HOUDIN~1.509/houdini/python2.7libs\houpythonportion.py", line 220, in createOutputNode

    exact_type_name)

  File "C:/PROGRA~1/SIDEEF~1/HOUDIN~1.509/houdini/python2.7libs\hou.py", line 22595, in createNode

    return _hou.Node_createNode(*args, **kwargs)

OperationFailed: The attempted operation failed.

Invalid node name

import toolutils

# If there is a node selected, then execute the code
if hou.selectedNodes():
    # Set the selected node to be the source node
    source_node = hou.selectedNodes()[0]
    
    # Create the Null SOP output for the source geo
    start_node = toolutils.genericTool(kwargs, 'null', 'OUT_GEO')
    start_node.setInput(0, source_node)
    start_node.setPosition(source_node.position())
    start_node.move([0, -1])
    start_node.setColor(hou.Color([0, 0, 0]))

    # Create a VDB From Polygons node to turn the source geo into a fog volume geometry
    fog_node = start_node.createOutputNode('vdbfrompolygons', 'create fog volume')

[graham]

You are trying to create a node whose name has spaces in it, "create fog volume", which isn't allowed in Houdini. You need to use underscores: "create_fog_volume".

[venator11387]

I knew it had to be a noob mistake like that   Thank you!