scons cant find iulib library

Question

iulib is already installed in /usr/local/include.But scons fails to find it

### iulib

env.Append(LIBPATH=["${iulib}/lib"])

env.Append(CPPPATH=["${iulib}/include"])
env.Append(LIBS=["iulib"])
assert conf.CheckHeader("colib/colib.h",language="C++")
assert conf.CheckLibWithHeader('iulib','iulib/iulib.h','C++')


-----------------------------------------------------------

Checking for C++ library iulib... no
AssertionError: :

assert conf.CheckLibWithHeader('iulib','iulib/iulib.h','C++')

Please suggest a solution for this..