On a comment below you stated that you are using OpenCV b5a . I just found a message from 2006 that mentions this version, which means you are using a jurassic release of OpenCV and that’s probably the root of the problem.
(due to broken link, here’s similar discussion: [Mingw-users] Problem On Compiling opencv with MinGW )
v2.0 was released in 2009 (after 2006), so “b5a” is either v1.x API or a beta/alpha, before v1.0. That is terrible.
You could see about finding a release from that era, but good luck getting that to compile, except in a period-accurate build environment.
or just develop on the target machine.
or ditch whatever’s requiring this version of OpenCV and replace it with something that isn’t old enough to drink and drive.
sorry, no good news.