configure timers in 64-bit mode with SYS/BIOS

hello everybody,

i'm trying to configure Timers in SYS/BIOS in 64-bit mode, but i get the following error:(i tried different timers but in vain)
                                         ti.sysbios.timers.timer64.Timer : Unsupported mode: 0 is specified for Timer: 1  

my code in the xdc script is as follows:

                                        var timer = xdc.useModule('ti.sysbios.timers.timer64.Timer');
                                        timer.timerSettings[1].mode = timer.Mode_64BITGPTIMER;

i have to mention that i configured my timers in 64-bit gp mode using CSL correctly, so it's not a matter of timers not supporting this mode.

i am using evm6474 (C64p family) with CCS 4.2.

regards.