Working to create a colored chart that when an alarm is acknowledged, the system generates a new message with the user's ID, otherwise it is blank. The color change is expected to occur when the field is not ""
<format type="color" field="AckID">
<colorPalette type="expression">case(not like(value,""),"33FF33")</colorPalette>
This works as a regular like expression, but unsure how to get it to work for something other than a blank field.