can't building file using petsc
 

HI,

I have just installed petsc, and then I run a given example within the petsc successfully.
However, I failed to run it if I copy the example to my workspace from petsc's original directory. Here are the partly output messages:
/home/cfd/usr/lib/libpetsc.a(comm.o): In function `PCTFS_grop(double*, double*, int, int*)':
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:206: undefined reference to `MPI_Send'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:209: undefined reference to `MPI_Recv'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:221: undefined reference to `MPI_Send'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:224: undefined reference to `MPI_Recv'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:237: undefined reference to `MPI_Send'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:240: undefined reference to `MPI_Recv'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:250: undefined reference to `MPI_Recv'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:253: undefined reference to `MPI_Send'
/home/cfd/usr/lib/libpetsc.a(comm.o): In function `PCTFS_grop_hc(double*, double*, int, int*, int)':
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:304: undefined reference to `MPI_Send'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:307: undefined reference to `MPI_Recv'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:324: undefined reference to `MPI_Send'
/home/cfd/installing/petsc-3.3-p6/src/ksp/pc/impls/tfs/comm.c:327: undefined reference to `MPI_Recv'