The workflow variables are potentially unused (not defined in workflow) ?

Dear KNIMErs,

 

I have a question regarding a warning that I am getting while executing headless KNIME workflow from command line in Linux. I always get such line:

 

The workflow variables are potentially unused (not defined in workflow): 
"Result_Folder_Filepath" (STRING)

 

listing variables that I have just overriden in a command line exeuction. However, the statement is not true because the variables are indeed used in the workflow. Why is that ?

Is this variable defined on the workflow level or created by a node in the workflow? You can only override variables defined on the workflow via the command line.
 

I first misunderstood your answer, but now I am on the right track. Thank you!