Re: compilation problem - variable was not declared in this scope

Can anyone look at this code and let me know why pthread_mutex_unlock
and pthread_mutex_lock are giving me the "phtread_mutex_unlock" was
not defined in this scope error.
I am compiling the code on g++.
[root@localhost Stargate_GPS]# g++ -v
Using built-in specs.
Target: i386-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --
infodir=/usr/share/info --enable-shared --enable-threads=posix --
enable-checking=release --with-system-zlib --enable-__cxa_atexit --
disable-libunwind-exceptions --enable-libgcj-multifile --enable-
languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --
disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-
gcj-1.4.2.0/jre --with-cpu=generic --host=i386-redhat-linux
Thread model: posix
gcc version 4.1.1 20070105 (Red Hat 4.1.1-51)

The header file is:
----------------
#ifndef UDP_COMM_H
#define UDP_COMM_H

// General Requirements
#include <iostream>

// UDP requirements
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
// Serial requirements
#include <stdio.h> // Standard input/output definitions
#include <string> // String function definitions
#include <unistd.h> // UNIX standard function definitions
#include <fcntl.h> // File control definitions
#include <termios.h> // POSIX terminal control definitions