Welcome to the forum!
Ok, my attempt to open the file produced an error:
Traceback (most recent call last):
File "dxf_input.py", line 530, in <module>
inkex.errormsg(_('%d ENTITIES of type POLYLINE encountered and ignored. Please try to convert to Release 13 format using QCad.') % polylines)
NameError: name '_' is not defined
I'm not very good at understanding the error messages, but it looks like Inkscape wants the DXF to be saved with a different DXF version. Does your program offer that version?
Note that I could be wrong with that assessment. But at least it's something to look at before someone more knowledgeable comes along.