Hi Alexandr, there are a few issues with the shaping of your curves, notice from the front view these little extra poking out pieces:



Those are sticking out because the curves are kind of hooked and bend inwards sort of like this:






I've attached a 3DM file that has some of that tuned up, but it's still problematic to try and use Sweep for it due to the fairly large flat areas that you have at the ends of the sweep.

For things that have big flat areas like that with blending between them, it tends to be better to model the flat areas first and then use fillet to put in the blended parts rather than trying to do a multi-blending type shape all in one single go with sweep like you are trying to do here.

The fillet method would go more like this - start with a narrow box:



Then select these edges:



And fillet them with a larger radius value to get this result:



Now select these edges:



And fillet them with a somewhat smaller radius than was used for the previous one, to get this:



Is that the kind of shape that you are trying to build?

It tends to be difficult to control surfacing commands like sweep when you are trying to put in multiple bended areas in the sweep all in one shot, it tends to be better to make sweeps be more one broad shape and if there are any tighter bends in it the tighter bends are usually better to do as fillets.

- Michael