Error loading dylib in 5.1.4 on Snow Leopard

I'm getting an error from dlcompat.c when I try to run an external that's linking to a dylib in /usr/lib. Works fine under 10.5 and Max 5.0.8.

"Can not open libisense.dylib".

Which means this line:
module = (void *)NSAddImage(path, NSADDIMAGE_OPTION_RETURN_ON_ERROR);

is returning NULL. I thought it was maybe because NSAddImage was deprecated in 10.6 but the test program still runs from the command line. It's only when I try to run it in the latest version of Max that it fails.

Any ideas why this would be happening? Did something change regarding security settings or path settings that prevents Max from loading a dylib from /usr/lib?

/* dlopen */
void *dlopen(const char *path, int mode)
{
    void *module = 0;
    NSObjectFileImage ofi = 0;
    NSObjectFileImageReturnCode ofirc;
    static int (*make_private_module_public) (NSModule module) = 0;
    unsigned int flags = NSLINKMODULE_OPTION_RETURN_ON_ERROR | NSLINKMODULE_OPTION_PRIVATE;

    /* If we got no path, the app wants the global namespace, use -1 as the marker
     in this case */
    if (!path)
    {

        return (void *)-1;
    }

    /* Create the object file image, works for things linked with the -bundle arg to ld */
    ofirc = NSCreateObjectFileImageFromFile(path, &ofi);
    switch (ofirc)
    {
        case NSObjectFileImageSuccess:
            /* It was okay, so use NSLinkModule to link in the image */
            if (!(mode & RTLD_LAZY)) flags += NSLINKMODULE_OPTION_BINDNOW;
            module = NSLinkModule(ofi, path,flags);
            /* Don't forget to destroy the object file image, unless you like leaks */
            NSDestroyObjectFileImage(ofi);
            /* If the mode was global, then change the module, this avoids
             multiply defined symbol errors to first load private then make
             global. Silly, isn't it. */
            if ((mode & RTLD_GLOBAL))
            {
             if (!make_private_module_public)
             {
             _dyld_func_lookup("__dyld_NSMakePrivateModulePublic",
                (unsigned long *)&make_private_module_public);
             }
             make_private_module_public(module);
            }
            break;
        case NSObjectFileImageInappropriateFile:
            /* It may have been a dynamic library rather than a bundle, try to load it */
            module = (void *)NSAddImage(path, NSADDIMAGE_OPTION_RETURN_ON_ERROR);
            break;
        case NSObjectFileImageFailure:
            post("Object file setup failure : "%s"", path);
            return 0;
        case NSObjectFileImageArch:
            post("No object for this architecture : "%s"", path);
            return 0;
        case NSObjectFileImageFormat:
            post("Bad object file format : "%s"", path);
            return 0;
        case NSObjectFileImageAccess:
            post("Can't read object file : "%s"", path);
            return 0;
    }
    if (!module)
        post("Can not open "%s"", path);
    return module;
}