I want to use an external subroutine in my UMAT but I have not been able to do that so far. Having created a dynamic library project in Visual Studio 2008, I have created a .dll and .lib files and copied the .lib file into the working directory of my abaqus job and the .dll file to exec folder. I have also added the directory of the .lib file in the LIB environmental variable. But I get these errors from ABAQUS: 

LINK : fatal error LNK1181: cannot open input file 'Dll2.lib' Abaqus Error: Problem during linking - Abaqus/Standard User Subroutines.   This error may be due to a mismatch in the Abaqus user subroutine arguments.   These arguments sometimes change from release to release, so user subroutines   used with a previous release of Abaqus may need to be adjusted. Abaqus/Analysis exited with errors

These are the changes I have made to the Environment file abaqus_v6 for Dll2.lib: 

link_sl='cmd /c "LINK /nologo /INCREMENTAL:NO /subsystem:console /machine:X86 /NODEFAULTLIB:LIBC.LIB /NODEFAULTLIB:LIBCMT.LIB /DEFAULTLIB:OLDNAMES.LIB /DEFAULTLIB:LIBIFCOREMD.LIB /DEFAULTLIB:LIBIFPORTMD.LIB /DEFAULTLIB:LIBMMD.LIB /DEFAULTLIB:MSVCRT.LIB /DEFAULTLIB:kernel32.lib /DEFAULTLIB:user32.lib /DEFAULTLIB:advapi32.lib /FIXED:NO /dll /def:%E /out:%U %F %A %B Dll2.lib &&mt /manifest %U.manifest /outputresource:%U;2 && del %U.manifest"' 

compile_fortran=['ifort', '/c', '/Gm', '/recursive', '/nologo', '/heap-arrays:1', '/include:%I','Dll2.lib'] 

One step backward, the weird thing is when I copied the .lib file to another directory like: 

link_sl='cmd /c "LINK /nologo /INCREMENTAL:NO /subsystem:console /machine:X86 /NODEFAULTLIB:LIBC.LIB /NODEFAULTLIB:LIBCMT.LIB /DEFAULTLIB:OLDNAMES.LIB /DEFAULTLIB:LIBIFCOREMD.LIB /DEFAULTLIB:LIBIFPORTMD.LIB /DEFAULTLIB:LIBMMD.LIB /DEFAULTLIB:MSVCRT.LIB /DEFAULTLIB:kernel32.lib /DEFAULTLIB:user32.lib /DEFAULTLIB:advapi32.lib /FIXED:NO /dll /def:%E /out:%U %F G:\\lib\\Dll2.lib %A %B &&mt /manifest %U.manifest /outputresource:%U;2 && del %U.manifest"' 

compile_fortran=['ifort', '/c', '/Gm', '/recursive', '/nologo', '/heap-arrays:1', '/include:%I','G:\\lib\\Dll2.lib'] 

I get this error which means the compiler or the linker do not recognize the .lib file I think: 

Creating library standardU.lib and object standardU.exp aba_test.obj : error LNK2019: unresolved external symbol _IDENTITY@8 referenced in function _UMAT standardU.dll : fatal error LNK1120: 1 unresolved externals Abaqus Error: Problem during linking - Abaqus/Standard User Subroutines.  

This error may be due to a mismatch in the Abaqus user subroutine arguments.   These arguments sometimes change from release to release, so user subroutines   used with a previous release of Abaqus may need to be adjusted. Abaqus/Analysis exited with errors where subroutine identity is what I use in umat subroutine. I would appreciate if you all can help me. And can you introduce a source where the process is explained in details?

I am using intel, version 11.1.048, VS2008 and Abaqus 6.11. I have also taken care of !dec\$ statements in both subroutines UMAT and IDENTITY.

Thank you.