Hi, I am now trying to use MS MPI after compiling with PETSc. I was using MPICH before. During linking, I got the error: 1>Compiling manifest to resources... 1>Microsoft (R) Windows (R) Resource Compiler Version 6.1.6723.1 1>Copyright (C) Microsoft Corporation. All rights reserved. 1>Linking... 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB1 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB1 imported 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB2 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB2 imported 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB3 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB3 imported 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB4 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB4 imported 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB7 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB7 imported 1>libpetsc.lib(somefort.o) : warning LNK4049: locally defined symbol MPIFCMB8 imported 1>libpetsc.lib(f90_fwrap.o) : warning LNK4049: locally defined symbol MPIFCMB8 imported 1>libpetsc.lib(pinit.o) : error LNK2019: unresolved external symbol MPI_Reduce_scatter_block referenced in function PetscMaxSum 1>libpetsc.lib(mpits.o) : error LNK2001: unresolved external symbol MPI_Reduce_scatter_block 1>C:\Obj_tmp\ibm3d_IIB_mpi\Debug\ibm3d_IIB_mpi.exe : fatal error LNK1120: 1 unresolved externals 1> May I know what's wrong? -- Thank you Yours sincerely, TAY wee-beng