Hi Peter,
maybe you are using SciTE? SciTE does not work correctly any more since some o2 editions. Oxygen.properties in folder IDE worked with me with Oxygenbasic of Febrary 2015. Most of the time I use PSPAD so I did not realize the difference.
I was successful with these changes in \IDE\Oxygen.properties:
##
# OXYGEN TOOLS
#
# COMPILE
basco=$(SciteDefaultHome)\gxo2 -c "$(FileNameExt)"
#
# BUILD
basbo=$(SciteDefaultHome)\co2 -a -c -m "$(FileNameExt)"
# RUN FROM SOURCE
basgo=$(SciteDefaultHome)\gxo2 "$(FilePath)"
#
# CONTEXT HELP
basho=hh.exe "$(SciteDefaultHome)\inf\oxygen_help.chm::/wordlink.htm#$(CurrentWord)"
#
For BUILD I use co2 because -a and -i are disabled with gxo2.exe
The difference is removing the quotes from the first argument of COMPILE, BUILD, RUN.
I tried calling gxo2.exe and .o2bas file in different ways in a console window but everything works ok. Do you call gxo2.exe from a batch file?
Roland