directMapped-nearestFace doesn't work
 

Dear all,
Who has used the nearestFace method in directMapped . My nearestFace doesn't work, but nearestCell works fine.
The following is my boundary file set:

5
(
inlet
{

type directMappedPatch;
nFaces 30;
startFace 27238;
sampleMode nearestFace;
sampleRegion region0;
samplePatch none;
offset ( 0.05 0 0 );
}
outlet
{
type patch;
nFaces 57;
startFace 27268;
}
upperWall
{
type wall;
nFaces 275;
startFace 27325;
}
lowerWall
{
type wall;
nFaces 302;
startFace 27600;
}
frontAndBack
{
type empty;
nFaces 27570;
startFace 27902;
}
)


but I have error message :

Starting time loop

Reading/calculating field UMean

Reading/calculating field pMean

fieldAverage: starting averaging at time 0

Time = 1e-05

Courant Number mean: 0 max: 0.2


start 27238 out of range 0 ... 29#0 Foam::error::printStack(Foam::Ostream&) at ~/OpenFOAM/OpenFOAM-1.6/src/OSspecific/POSIX/printStack.C:203
#1 Foam::error::abort() at ~/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/error.C:242
#2 Foam::Ostream& Foam::operator<< <Foam::error>(Foam::Ostream&, Foam::errorManip<Foam::error>) at ~/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/errorManip.H:87
#3 Foam::UList<Foam::Vector<double> >::checkStart(int) const at ~/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/UListI.H:82
#4 Foam::SubList<Foam::Vector<double> >::SubList(Foam::UList<Foam::Vector<double> > const&, int, int) at ~/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/SubListI.H:61
#5 Foam::List<Foam::Vector<double> >::subList const Foam::fvPatch::patchSlice<Foam::Vector<double> >(Foam::List<Foam::Vector<double> > const&) const at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/fvPatch.H:191
#6 Foam::directMappedFixedValueFvPatchField<Foam::Vec tor<double> >::updateCoeffs() at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/fields/fvPatchFields/derived/directMappedFixedValue/directMappedFixedValueFvPatchField.C:267
#7 Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>::GeometricBoundaryField::updateCoef fs() at ~/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/GeometricBoundaryField.C:271
#8 Foam::fvMatrix<Foam::Vector<double> >::fvMatrix(Foam::GeometricField<Foam::Vector<doub le>, Foam::fvPatchField, Foam::volMesh>&, Foam::dimensionSet const&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/fvMatrix.C:230
#9 Foam::fv::gaussLaplacianScheme<Foam::Vector<double >, double>::fvmLaplacianUncorrected(Foam::GeometricFi eld<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) in "/home/panda60/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPDebug/libfiniteVolume.so"
#10 Foam::fv::gaussLaplacianScheme<Foam::Vector<double >, double>::fvmLaplacian(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/finiteVolume/laplacianSchemes/gaussLaplacianScheme/gaussLaplacianSchemes.C:114
#11 Foam::fv::laplacianScheme<Foam::Vector<double>, double>::fvmLaplacian(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/laplacianScheme.C:108
#12 Foam::tmp<Foam::fvMatrix<Foam::Vector<double> > > Foam::fvm::laplacian<Foam::Vector<double>, double>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&, Foam::word const&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/fvmLaplacian.C:220
#13 Foam::tmp<Foam::fvMatrix<Foam::Vector<double> > > Foam::fvm::laplacian<Foam::Vector<double>, double>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/fvmLaplacian.C:252
#14 Foam::tmp<Foam::fvMatrix<Foam::Vector<double> > > Foam::fvm::laplacian<Foam::Vector<double>, double>(Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) at ~/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude/fvmLaplacian.C:264
#15 Foam::incompressible::LESModels::GenEddyVisc::divD evBeff(Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) const at ~/OpenFOAM/OpenFOAM-1.6/src/turbulenceModels/incompressible/LES/GenEddyVisc/GenEddyVisc.C:95
#16 Foam::incompressible::LESModel::divDevReff(Foam::G eometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) const at ~/OpenFOAM/OpenFOAM-1.6/src/turbulenceModels/incompressible/LES/LESModel/LESModel.H:240
#17 main at ~/OpenFOAM/OpenFOAM-1.6/applications/solvers/incompressible/pisoFoam/pisoFoam.C:70
#18 __libc_start_main in "/lib/libc.so.6"
#19 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/i386/elf/start.S:122


From function UList<T>::checkStart(const label)
in file /home/panda60/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude/UListI.H at line 78.

FOAM aborting

Who has ued this ,could give me some suggestions ? Maybe my set is not right.
Thanks.