pthread_mutexattr_getprioceiling error?

[Михаил Кипа]

Next little program:
#include <pthread.h>
#include <iostream> 

int main()
{
        pthread_mutexattr_t t;
        if (pthread_mutexattr_init(&t)) return 1;
        int i;
        std::cout << pthread_mutexattr_getprioceiling(&t, &i) << std::endl;
}

always print 22. It means that pthread_mutexattr_getprioceiling always fails with EINVAL. Under Linux this example works fine, but under FreeBSD 7.2 it does`n work. Is it a bug in FreeBSD thread library or it ai my misunderstanding?