experimental macarons

yesterday i had a wee go at making macarons. kept seeing the damn things everywhere and as far as im aware there is nowhere in glasgow to buy them. i did find out tho that laduree have a shop at harrods in london http://www.laduree.fr/public_en/maisons/londres_accueil.htm i mite have to give em a quick call to order some if i or we cant crack the recipe. but im trying not to be too dissapointed. from what ive read over the last few days making these lil belters doesnt come easy to most and there are a few set rules or things to bear in mind. above and to the left you can see what happened to mine. they cracked and they cracked bad. they are not meant to do that. see the other pic as to how they should look. i used the recipe from serious eats (mel advised me to)
http://www.seriouseats.com/recipes/2007/10/how-to-make-macarons-recipe.html
so what went wrong. i think that it could have been one or all of a number of things.
1. i may have overbeat the eggwhites.
2. i may have overbeat the eggwhites with the icing sugar and almond meal.
3. my oven could have been too hot or cold.
4. i may need to age my eggswhites for longer.
if none of this makes sense read the serious eats link above. lots of good info can also be found here:http://www.syrupandtang.com/200712/la-macaronicite-1-an-introduction-to-the-macaron/
ach well i might have another go this week or better still let mel try.