And a very nice car too. I have always liked the Mk.2 Toledo, which was the car from which the Mk.1 Leon was derived - but the Toledo is lighter (that tailgate is *heavy*) and stiffer. And I like the lines better too, but that's just me. I've had two, a TDI 110 and the lovely TDI 150 Sport.
Anyway, I did wonder if the OP had a compatible transmitter fob, but it can be hard to tell. Glad he got it sorted.
And, just to complete the observations, both the original keys have a transponder chip - they have to otherwise the immobiliser would stop the car. In the "dumb" key it is glued right next to the key blade in the plastic handle, just like in the "smart" key with the remote transmitter attached to it. In the past, lots of folks have upgraded to a flip key by taking the transponder out of the "dumb" key after matching the remote fob.
