New Rule for Next Set of Point Sheets

I am having a hard time getting some students to return their point sheets with a parent/guardian signature. Returning signed point sheets and other work is an important aspect of participating in my class. I give 50 extra-credit participation points each grading period as a reward for good participation and I deduct from those points when a student does not meet my expectations for participation. One of my class rules is to "follow directions the first time." Starting with the next point sheet (coming soon) I will give my usual five-point grade for turning in the point sheet on time. Students may turn in the sheet for no credit the following day. For every day after that I will deduct five participation points until the point sheet is returned with a parent signature or the participation points are eliminated. At that point I will write a referral for "failure to follow a reasonable request." I will also apply this rule to other forms requiring a signature. I hate to have to be tough about this, and many of you are great about returning point sheets and other forms. However, I must find a way to motivate those students that consistently fail to follow instructions.