Install aliroot

Dear support,
It showed following error information when I install aliroot.
Please help me.

Thank you very much.

sija

***** Compiling STEER/AliRun.cxx *****
STEER/AliRun.cxx: In constructor AliRun::AliRun(const char*, const char*)': STEER/AliRun.cxx:220: cannot allocate an object of typeAliStack’
STEER/AliRun.cxx:220: because the following virtual functions are abstract:
/sci/root/include/TVirtualMCStack.h:48: virtual void
TVirtualMCStack::PushTrack(int, int, int, double, double, double, double,
double, double, double, double, double, double, double, TMCProcess, Int_t&,
double, int)
/sci/root/include/TVirtualMCStack.h:56: virtual TParticle*
TVirtualMCStack::PopNextTrack(Int_t&)
/sci/root/include/TVirtualMCStack.h:57: virtual TParticle*
TVirtualMCStack::PopPrimaryForTracking(int)
/sci/root/include/TVirtualMCStack.h:77: virtual TParticle*
TVirtualMCStack::GetCurrentTrack() const
/sci/root/include/TVirtualMCStack.h:80: virtual Int_t
TVirtualMCStack::GetCurrentTrackNumber() const
/sci/root/include/TVirtualMCStack.h:83: virtual Int_t
TVirtualMCStack::GetCurrentParentTrackNumber() const
gmake: *** [STEER/tgt_Linux/AliRun.o] Error 1