Sergei,
There is probably some mismatch in the Fortran compiler you are using
compared to the one we used for our Fortran examples. Typically
function headers and other things may need to change depending on the
Fortran compiler you are using when calling a C library from Fortran.
You should look in the ifort manual to see how the KNITRO C function
headers should be defined and then make the appropriate changes to
the "knitro_fortran.c" interface file.
-Richard