I am not sure I understand the problem exactly - but here are some suggestions.

In picture 1 - the file extension box is always blank unfortunately- there is now way for the ruby scripts to control it in Sketchup, but it shouldn't matter.

In picture 2 - the dialog box indicates that no faces were exported, but 4 lines were. Looking at your model there are no faces - only lines. It might be that you tried to export the model as a polyface mesh or triangular mesh - this would not work if there were no faces. I should have the script generate an error message in this case.

I picture 3 - there appears to be no DXF file extension on your saved file, which is why A9CAD will not open it in picture 4. Perhaps you could manually rename the file and add the DXF extension?

I have had reports of problems saving the files when there are non-latin characters in the folder location - this might be related to your problem given that your computer's language is Russian.

I hope this is of some help to you,

Nathan