Ladder 65 was alerted for a cover assignment for Bucks Station 18 while they operated at a working dwelling fire in Richland Township.  While enroute, Chief 65 (Seip) was alerted that Squad 65 was due as an additional RIT company on the assignment.  Before the Squad responded Bucks Radio advised that Quakertown Command did not need the additional RIT so Ladder 65 responded to cover 18's.  The Ladder with a crew of 6 stood by for about 4 hours before returning to service in Pennsburg.  While on cover, 65's was alerted for a smoke in the area call.  Asst. 65-1 (Latshaw) investigated but could not find any problem.