The top of the bread caves in uless I use a box mix ! what am I doing wrong?

Do you mean the loaf rises ok, then during the cooking cycle collapses?
if so, you will have to alter the mix.
First try using less yeast. Adding a little more salt may also help.

Hi, This link may be helpful to you...Hank

http://www.kingarthurflour.com/tips/bread-machine-basics.html

Are you letting the bread cool thoroughly before removing from the pan? Also, sourdoughs tend to cave in as well. You could also have too much liquid in your mix - try reducing your liquid by a tbsp at a time. Too wet of dough will cave after baking.

This also happened to me. I found out that the yeast in the box was out of date! Now I just use a new packet of equivilent size in any mix I use and have solved that particular problem.

Try to buy bread mixes that are in proportion to your machine. I had a machine that mads 2-1/2 pound loaves. I could only find mixes for 3/4 pound loaves. I had to buy multiple mixes, put them together and divide them by weight. I gave the machine away.

I am having the same problem, I have made 3 loaves of white, they all did not turn out, and I played with the recipe a bit to solve it, but I keep getting the same result!

I had a similar problem when I switched machines. It seems that most recipes will work in same size machines (1 or 1.5 lb loaf size). My issue was that my old machine had to have liquids in first and then dry ingredients (new machine is the opposite). I ruined several loaves before I figured out the issue. I would have never imagined the order of ingredients would make a big difference.
Good luck!

Here's a good basic white bread recipe that works great with a BD2550 (and usually doesn't even **** the mixing blade into the bottom of the machine

1 cup warm (not hot) water
1/3 cup milk
1 tablespoon sugar
1 teaspoon salt
1 1/4 tablespoons butter/margarine
4 cups flour
1 teaspoon yeast

Heat the water and add the milk to it. Dissolve the sugar and salt into this mix and pour the liquid into the bottom of the bread maker bucket (make sure the mixing blade is already in). Melt and add the butter to this mix. Add the 4 cups of flour directly on top, but do not mix it in. The flour will float on top of the liquid. Make a small dimple in the top of the flour in the middle with your finger and add the yeast into that little crater (at no point while adding ingredients do you let the yeast touch the liquid). Set the bread maker for basic setting 1, light crust, 2lb loaf and let it do it's thing. 3 hours later, you'll have a nice loaf of white bread with good consistency and density, and it usually leaves the mixing blade in the bucket (rather than having to dig it out of the loaf after).

Hope this helps!

Likely, your loaf is too wet.
This can happen with as little as 1 Tablespoon too much liquid. It's hard to describe "the look," but what I learned to do was to watch the bread during the initial mixing cycle (after the paddle begins to turn full circles). The dough should not stick to the side of the pan while mixing, and it should look elastic, but not shiny. If it looks shiny, there's too much liquid in relationship to flour. I add a tablespoon of flour at a time during the mixing cycle, until I get a good consistency.
There's nothing wrong with the taste of the sunken loaves. We usually just shrug and eat them anyway.

Look at the box first. Many times it will have instructions on it. However sometimes it may not and have only the the dry ingredients. If the box has no instructions, see how many cups of flour the mix uses. If it uses 3 cups of flour total, the mix is for a 1 1/2 pound loaf. If the mix uses 2 cups of flour it will make a 1 pound loaf. Box missing this info? It's time to take the flour out of the box to measure it with at measuring cup. Mixes sometimes combine all the ingredients together so it will measure bit more than 3 cups for a 1 1/2 pound loaf or 2 cups for 1 pound loaf. After finding out how big the loaf is going to be then get the bread pan and instruction manual and start constructing the dough. I'd find the recipe in the manual that matches the mix the best to find out how much liquid to use. (for a classic whit its 1 cup for 1 1/2 pound leaf and 3/4 cup for 1 pound loaf) Then I put the liquid in the pan first along with butter (if necessary), followed by the dry ingredients in the mix with the yeast at the top. Put the pan into the bread machine and select 1 or 1 1/2 loaf or if it is a french or sweet bread. Press start. Unfortunately I have a different machine than you do, but I think this will help.