Shift lock system
To shift the transmission from P (Park) into R (Reverse):
If the brake pedal is repeatedly depressed and released with the shift lever in the P (Park) position, a chattering noise near the shift lever may be heard. This is a normal condition.

Always fully depress the brake pedal before and while shifting out of the P (Park) position into another position to avoid inadvertent motion of the vehicle which could injure persons in or around the vehicle.
Your vehicle is designed to go into a protective mode if the driver inadvertently selects the R (Reverse) gear while the vehicle is being propelled forward. If this occurs, the engine, power brakes and power steering will all deactivate. This mode is designed to alert the driver to the gear-selection error and prevent damage to the transmission.

Confirm the desired gear position is selected when driving on a graded road. If the protective mode is triggered on an incline, the driver may not become aware that the power braking and steering have been turned off which can increases the risk of an accident.
Shift-lock override

If the shift lever cannot be moved from the P (Park) position into R (Reverse) position with the brake pedal depressed, continue depressing the brake, then do the following:
If the shift lever does not move even after performing this procedure, have the system inspected by an authorized Kia dealer.