Cannot open include file:problem with Dll header

i am trying to use dll for my project..i have include "test.lib" in
link tab in project
And now i want to use function of dll by including "test.h" file in
stdfx.h.
but while compile it gives error .
Cannot open include file: Cannot open include file: `test.h` no such
file or directory
Any help........how to solve this problem

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