gps_coreSetOpts() returns GPS_ERR_INVALID_PARAMETER

Hello,
I can’t understand why the function gps_coreSetOpts() reports invalid parameters (i.e eRetStatus = -3)!
I’m using this syntax :
eRetStatus = gps_coreSetOpts(GPS_OPT_CORE_RUNNING_POWER_MODE, GPS_PM_VERY_LOW,GPS_OPT_END);
I have checked that I’m compliante with API restrictions (especially lib GPS state. In my case, the lib is in running mode). But always the same error.

modem is a FX100 with these version :
-“Developer Studio”,“3.6.0.201511091706”
-“Open AT Application Framework package”,“2.53.0.201504010915”
-“Open AT OS Package”,“6.53.0.201503311458”
-“Firmware Package”,“7.53.0.201502160745”
-“ExtendedATApplication Library Package”,“1.3.2.201502131016”
-“Location Library Package”,“1.4.7.201401140843”
-“AirVantage Agent Library Package”,“5.3.4.I201408221554”
-“Security Library Package”,“2.2.0.201306261000”
-“Internet Library Package”,“5.57.0.201502130730”

Any ideas?