Thank you bemfarmer,

I mean all areas of the entire (front) object.
So the entire object.
The loft is not the problem, just as the main body.
But all three objects to merge into one and then get 1 object,
turns out to be difficult for me.

In the picture you can see what I mean.
The solution of the problem lay in the open edge.
After re build the curves, there were no more problems.
I do not understand how these open-edge form.

Hope you can understand my english :)

-----------------------------------------------
*edit

We're talking about the front part, which consists of 3 parts.
The goal is to merge the three parts to one part in order then to round the edges.

After connecting the parts now is a small hole between the red and the orange part.
But it is a closed surface. What I understand there is not or what I'm doing wrong.

The first picture shows the hole between the surfaces.
The second picture shows the staggered edge.

 

I always need some time to read the articles here and understand ...
and it is now 1 night clock. I must go to bed.

Good night and thank you for your help.
I look at us again tomorrow.