Go CCIE Go!! - A Cisco Certified Internetwork Expert

Hi all experts,
Is it mandatory to turn on frame-relay shaping when running MLPoFR?
According to DocCD, the FRTS is prerequisite for MLPoFR, I am wondering the rationale might relate to QoS topic it describes.
Practically, I tried the MLPoFR *without* enabling FRTS, it still works fine. However, the router prompt me the following error message if I do not enable FRTS.
Could anybody share his experience when dealing with MLPoFR? What is the consequence if I do not turn on FRTS?
Regards, CH
*Remark* ———————————————————————————————————————————————————————————————— (Using Multilink PPP over Frame Relay) http://www.cisco.com/en/US/docs/ios/12_4/qos/configuration/guide/qslfifr.html#wp1064366,
12.3(22) Router1# *Mar 1 02:29:25.887: %FR-3-MLPOFR_ERROR: MLPoFR not configured properly on Link Virtual-Access1 Bundle Multilink34 :Frame Relay traffic shaping must be enabled *Mar 1 02:29:25.899: %FR-3-MLPOFR_ERROR: MLPoFR not configured properly on Link Virtual-Access2 Bundle Multilink34 :Frame Relay traffic shaping must be enabled
12.4(18) Router2# *Mar 30 09:16:17.835: %LINK-3-UPDOWN: Interface Multilink35, changed state to down *Mar 30 09:16:17.911: %FR-3-MLPOFR_ERROR: MLPoFR not configured properly on Link Virtual-Access1 Bundle Multilink35 :Frame Relay traffic shaping must be enabled *Mar 30 09:16:17.915: %LINK-3-UPDOWN: Interface Multilink35, changed state to up *Mar 30 09:16:17.923: %FR-3-MLPOFR_ERROR: MLPoFR not configured properly on Link Virtual-Access2 Bundle Multilink35 :Frame Relay traffic shaping must be enabled