ZAU Controller described failed automated altitude hand off/point out procedures resulting in a potential conflict; the Reporter suggesting augmenting the procedure with verbal coordination.

Narrative

Per the LOA (Letter of Agreement) with ZID ARTCC the MDW arrivals will cross the boundary with LOGAN (34) at FL240. LOGAN (34) will take the hand off of the MDW arrival and flash the aircraft to the LOOTH (32) Sector. The RUSHVILLE (I75) Sector will then ship the aircraft to the LOOTH (32) Sector north of J80. A hard altitude of 240 will be in the Data Block if the MDW arrival will comply with the crossing and a 'T'd' altitude of 240 if the aircraft will not make the crossing. FA20 had a hard altitude of 240 however crossed the boundary at FL271 descending to FL240 with BE30 head on at FL250. I had to call LOOTH (32) to inform them that the T'd altitude was not used and we had traffic. I called RUSHVILLE (I75) they said they would call LOOTH and that they were sorry. This happens more times than I think are being reported. I believe if the LOA is not adhered to there will be an error because someone will forget to use the T'd altitude. I would like to see a phone call every now and then instead of a T'd altitude. This way if you know you are not making the crossing; and call LOGAN (34); this would help with any potential traffic.