I'm feeling very stupid but no matter where I look I can't find what I'm doing wrong. I want to display a ListboxField that contains all the values I've specified in my listboxArray array. The values are there alright, I just can't set it to multiple select. I only ever get a one-value dropdownlist...

I also would like to know how to set the $size to use the size value returned by getAttributes...

$fields = parent::getCMSFields();
		
		$fields->addFieldToTab("Root.Content.Main", new ListboxField(
			   $name = "Treatments",
			   $title = "All treatments offered by practitioner",
			   $source = $listboxArray,
			   $size=8,
			   $multiple=true
			   )
			);
   		return $fields;

What am I doing wrong?

OK to answer my own question I didn't realise value='', would be so important. Put that in and it works.

My question as to how to set the size to be that of the array still stands though!