How to update Connection Advertising Intervall ?

Hello,

I need some help with getting the CFG_FAST_CONN_ADV_INTERVAL_MIN and CFG_FAST_CONN_ADV_INTERVAL_MAX in app_conf.h

I am using Custom Template with Non connectable and no scan response.

I have tried to call

 ret = aci_gap_set_discoverable(
 ADV_TYPE,
		My_Advertising_Interval_Min,
		My_Advertising_Interval_Max,
 BLE_ADDR_TYPE,
 ADV_FILTER,
 0,
 0,
 0,
 0,
 0,
 0);

inside the app_ble.c and the function is called with return value of F and the Intervals are not updated.

Can someone help me please with this problem and Thanks in advanced.