Is the coil round or kind of a square-ish box ? if it's the box...you've been shafted, cause that's for a CDI ignition.
Also make sure it's not that damn Bosch 6V coil every shop seems to try foisting on Tomos owners.
Also, check the wiring all the way back...make sure your coil is hooked to the proper leads using a jumpline...the leads come out over on the other side of the trans...brown is ground, the rest are hotleads...usually yellow and/or black.
In addition, take some sandpaper and sand a spot on the cylinder till it's gleaming bare metal, and hold the plug against THAT when checking, the "paint" on a Tomos cylinder is somehow conduction-resistant...and therefore unless you have good contact with bare metal, it will not spark even if you are, in fact, getting spark.
That little bit of Tomos trivia drove me and Fred bonkers one night for a coupla minnits.