My sympathies to the OP - having anything stolen from you by a thief just plain sucks.
In the GTA area, Condo thefts are epidemic - the parking garage is nothing more than an indoor market of sorts for the light-fingered. There has been a serious problem with motorcycle theft rings for the past number of years who can be in and out of a parking garage in about 2 minutes flat with a motorcycle thrown into the back of a (stolen) van with bogus plates. When there are arrests made, it seems to be purely by chance .. otherwise they have operated pretty much with a free hand, with minimal Police investigation and intervention.
A fenced-in storage locker would present minimal challenge to all but the most casual, opportunity-knocks type thief.