The workflow variable is potentially unused (not defined in workflow): "filename" (STRING)

Trying to call application in batch mode and pass the filename to process.   I've setup my application to define a workflow variable using the "String Input" in the Quick Forms.

I run it and it doesn't take the variable I pass and I recieve the following error.

The workflow variable is potentially unused (not defined in workflow): "filename" (STRING)

Here is the command line I'm running.

/Applications/KNIME/Contents/MacOS/knime -nosplash -nosave \
	-application org.knime.product.KNIME_BATCH_APPLICATION \
	-workflow.variable=filename,/Users/edmckee/Downloads/knime.csv,String \
	-workflowDir=/Users/edmckee/Development/nodeProjects/redi_services/redi_knime/knime_workspace/redi_01/redi_01_12hr_class/