When buckling my 5 year old son into his booster seat, the rear seatbelt always becomes wedged in a cavity of the rear seat. this also occurs if my son moves while we are in transit. this causes the seatbelt to fail to retract properly and thus he is not properly secured. i am afraid not only for his safety because the seatbelt is not securing his torso properly. additionally, from this occurring frequently, i am afraid that wear on the seatbelt (fray) will compromise the seatbelt material causing it to fail if ever in a crash.