PedalDemo Error

Hi ~

I want to build the PedalDemo example by myself with the help of Totorials ,But i encountered a problem ,during the Lesson 7: Making Ends Meet ,then insert two simple drivers into the Drivers folder like those:
AnyFolder Drivers = {
AnyKinEqSimpleDriver PostureDriver ={
AnyKinMeasureOrg &Ref2 = …HumanModel.Interface.Trunk.PelvisThoraxLateralBending;
AnyKinMeasureOrg &Ref3 = …HumanModel.Interface.Trunk.PelvisThoraxRotation;
AnyKinMeasureOrg &Ref1 = …HumanModel.Interface.Trunk.PelvisThoraxExtension;
DriverPos = {0,0,0};
DriverVel = {0,0,0};

then reload the example ,the error as follow,i can not find the answer ,beg you help ,thank you very much!

Loading Main : “C:\Users\Administrator\Desktop\AMMR\Application\MyPedalModel\Pedal.Mian.any”
Constructing model tree…
ERROR(SCR.PRS1) : C:/U…s/A…r/D…p/AMMR/Body/A…n/T…k/Interface.any : ‘ref’ : Object already declared at :
C:\Users\Administrator\Desktop\AMMR\Body\AAUHuman\Trunk\Interface.any(102) : ‘ref’
Model loading skipped

ps: The using AnyBody is 5.3 ,the tutorial is Building block tutorial -->>Lesson 7: Making Ends Meet


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