frustared with cakes!

I personally have no help for you as it happens to me too, my other half and I call it the passover cakes (unleavened). I am thankful it isn't only me that it happens to. I used the Joy of Cooking recipe. Back to boxed cake I guess :(

Sadaf,

Don't give up!!

One good thing is that your problem is consistant. You are way ahead of somebody that gets different results every time.

I really think this is minor. If you are using a box mix you must follow the directions exactly how it's written. These companies

spend 1000;s of hours refining the recipe. If it says mix 3 min. then time it...    until you get a good product.

  I really think you need to check your oven temp. You can get a thermometer at the grocery store. Just make sure it goes up

to 500 deg. Put it in the middle of your cold oven. Set at 350 and wait to check.

If you have a knob, I will explain later how to adjust.

The box will tell you how to test the cake for doneness. If it looks done it could very well not be and sink when you take it out.

Also remember that opening the door during baking will reduce the temp.and it will take a while for the oven to go back up.

panini

Are you preheating your oven for at least 20 minutes?

Yes, i agree, either you're using a pan that is too big (the size is VERY important) or your oven is probably too cold.  The heat has to give it an initial shove towards rising.  Do test your oven and let it pre-heat a good long time. 

One thing many people have pointed out, though it never happened to me, is that your baking powder or soda is expired and has lost its leavening power.  (I think this is more likely if your container is not waterproof or is left open). 

Put your cake in the oven really quickly, dont let the heat out. Check the cake 5mins from full time and not before. Have an oven thermometer in the oven and watch what happens when you open the door. The thermostat on your oven might be faulty and the oven doesn't kick into gear quickly enough. Are they coming out a bit rubbery? Baking is a science and if you stray too far from the mark stuff goes wrong. Eggs are important. Some cakes work best if the eggs are more than a week old, but some work best if the eggs are straight from the chook house.

I have never heard of Soda going funny but I know that SR flour doesn't last long before it gets a bit funny. Humidity can play a part. If you have a gas oven things get a little harder to control. When you roast meat have you noticed hot spots. Gas tends to be much hotter at the top ( not saying gas is hotter than electric) but I am saying that gas ovens have greater temp differentials within them. New ones have a little more effort put in by manufacturers but old ones are notorious for uneven heat. 

Unless you're making a cake that depends on beaten egg whites for leavening, you don't need to beat the hell out of the eggs. They only need to be beaten enough to emulsify them - even leaving a few streaks of white shouldn't hurt, if they'll be beaten more inside the batter.

If you're using baking powder, try testing it to see if it's any good. Put about half a teaspoon into a cup of very warm water. If it foams up, the baking powder is good. If it doesn't, a new container of baking powder is in order.

If you're using self-rising flour, it could be that the leavening in the flour has gotten too old. Try using all-purpose, instead. Add 1 t. baking powder and 1/2 t. salt for each cup of flour called for in the recipe.

And, no, you can't really preheat an oven too long, as long as the thermostat is working. It shuts off when it gets up to temperature, then comes back on when it cools down some, so it should maintain a reasonably even temperature.

Which boxed recipe are you using? I sometimes have that problem myself due to the high calcium/mineral/arsnic content of my tap water. Maybe yours is a similar blunder? Try using bottled water.

Also, how old are your cake mixes? Maybe you just keep picking up old boxes from the store?