On March 13, 2004, about 1530 central standard time, a Piper PA-28R-200, N15118, piloted by a flight instructor and a dual student, was substantially damaged when the right main landing gear collapsed during landing rollout on runway 18 (6,000 feet by 100 feet, asphalt), at the Illinois Valley Regional Airport (VYS), Peru, Illinois. The dual student was a non-current private pilot receiving instruction in preparation for a flight review. The instructional flight was operating under 14 CFR Part 91 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. The flight instructor, dual student and passenger did not report any injuries. The local flight departed VYS approximately 1400. In his written statement, the dual student reported that they had practiced airwork in the local area prior to returning to VYS. He noted that the landing was smooth and after about a 300-foot ground roll, the instructor asked him to raise the flaps. He stated that he "inadvertently reached for the gear switch on the front panel instead of the flap lever between the seats. The gear switch was not moved to the complete up position before the instructor announced and I realized my error." He reported that the right main landing gear collapsed and the aircraft veered off the right side of the runway. The nose gear subsequently collapsed before the aircraft came to a stop. The flight instructor, in his written statement, reported that the dual student landed the aircraft "very smooth" on the runway centerline. He stated that during the landing roll he asked the student to raise the flaps, however, the student "accidentally grabbed the landing gear lever, probably pulling it at least partially out." A Federal Aviation Administration inspector conducted a post-accident inspection. With the aircraft elevated on jacks stands, the landing gear system was activated by using the cockpit gear switch and the landing gear retracted and extended as designed. The squat switch was determined to be installed and adjusted in accordance with the manufacturer's requirements. Electrical functionality of the switch was tested and no anomalies were observed.