You can use the TRiLOGI "Set PLC Real Time Clock" function under the "Controller" pull down menu to set the real time clock.
Once the real time clock is set to the value you defined, then you can use Online monitoring and click the "View Variable" to look at the new value of the RTC. It must work.
When you said "nothing happen" I think you are probably refering to what you display on the LCD? If your program does not refresh the LCD display regularly then the display will not show the new value even after you have set the new RTC data.