Why am I not able to exclude events from getting indexed with my current props and transforms.conf?

Not able to exclude events from indexing on Splunk Enterprise Free version. Can anyone help me out here? Sample data: Name:mango Name:Mango Name:ManGo Name:apple Name:banana Name:strawberry Name:pineapple props.conf [txt1] DATETIME_CONFIG = CURRENT NO_BINARY_CHECK = true SHOULD_LINEMERGE = false category = Custom pulldown_type = true TRANSFORMS-set= setnull transforms.conf [setnull] REGEX = mango DEST_KEY = queue FORMAT = nullQueue