IFSIO and print files

Trying to debug a program, that reads a source file from integrated file 
system, does something and must generate a report by writing data to PRTF.

As soon as I compiled the program with option *IFSIO, it started to read data 
from IFS stream file that was opened by command

IntrFile = fopen("QIBM/EURIBOR/myfile.txt", "r") ;

verything was fine until I started adding report generation.
I do it as usual: I have a *PRTF, that I normally use so:

LogFile = fopen("*LIBL/EQRPT", "w") ;
....
fwrite(szTemp, strlen(szTemp), 1, LogFile);

With *IFSIO it does not work, as LogFile always returns NULL with errno 3025 
(no such file or library). 

Very soon I understood that *IFSIO is "responsible" for the problem and I must 
use different notation.
Manual (Programmer's guide) advises to use 
/QSYS.LIB/LIB_NAME.LIB/FILE_NAME.FILE/MEMBER_NAME.MBR

OK. The only problem is that PRTF does not have members...

Tried 
IntrFile = fopen("/QSYS.LIB/KLIBEEK.LIB/EQRPT.FILE", "w") ;

returns NULL and errno 3021 (Invalid argument)

then tried 
IntrFile = fopen("/QSYS.LIB/KLIBEEK.LIB/EQRPT.FILE/EQRPT.MBR", "w") ;

returns NULL and errno 3403 (Not a directory).

I'm sure, that there must be a solution....

Jevgeni Astanovski