1) The HIN may also be located in the port transom corner (early Californian boats), or between the rudder fittings (early Canadian and later Californian boats - in the latter it may even be upside down!). Of course, these are extremely hard to miss if you've already checked the starboard corner.
2) If I've understood it right, the HIN coding was introduced in November 1972. There were close to 3000 Lasers built before that, and their identification consists of the sail number embossed under the bow eye fitting.
3) Your boat wasn't built in North America, which means it's coded in a different way. European-built (English/Irish/Swiss) boats continued with the sail number under the bow eye until 1983 or '84. Boats built in most other places had the sail number in the middle of the transom.
If you want to know more accurately how old your boat is, please take and post pictures of the transom, the blades, grabrails, and vang fittings on the spars and the vang blocks.
In addition to Rob and LaLi notes above, there is also the possibility that the number is all or partially obscured by the lower rudder gudgeon fitting on the transom, especially if it has been relocated over time.
Or, if the boat has been painted, that the serial number was faired in and is now very well hidden!