change a global attribute of a netcdf file

Dear users

i use the following script to change values of global attributes in an existing netcdf file:

myfile=['spinCGRID.ncf'];

nc = netcdf(myfile,'write');

nc.SDATE = nclong(2007354);

endef(nc);

close(nc);

although this used to work for several times, now i am having problems with it, the script runs but no change happens in the netcdf file. is there anotherway to do this?

thank you