I made a cake for my husband to take to work and it turned out perfect. I used a cake mix. A lady there wanted me to make one identical for her son's birthday. Total disaster. The tops of the cake layers were sticky to the touch and when I tried putting the icing on the sticky part mixed in with the icing. What caused this?
I went to the grocery store and bought everything again and started over. This cake flopped too. It cracked and the icing ran off. I don't think I let this one cool enough before trying to ice it.
Gave up and now we have two cakes at home to eat and my husband's co-worker doesn't have a birthday cake.
Sounds to me like maybe the cake didn't cook throughly (wetness) and you might have also opened the oven one to many times (flopping). I'm no expert that's just two of the things that may have turned out wrong.
Welcome to Cake Central.
The surface of a cake layer can be sticky. If you level the cake, you can often take that off. If you leave it on, use a crumb coat to control the crumbs in the icing. Use your regular icing, a bit thinner, cover the cake so it is smooth, with a thin layer of icing. you can chill it a bit to create a stable surface for the finishing icing.
You do need the cake to cool completely before icing. If you are anxious and short of time, a brief spell in the fridge can help.