mq_send and mq_receive seem blocked - no transmission seems to happen - c

Question

I am writing a producer/consumer app where one thread writes to the message queue while other consumes/reads from it, but it seems as if both the mq_send() and mq_receive() are blocked hence no transmission takes place.
In other words, I don't see the prints from either Transmit or Receive functions i.e Received buffer: %s or Sent...
#define MAX_MESSAGES 10
#define MAX_BUFF_SIZE 180
#define MSG_BUFF_SIZE MAX_BUFF_SIZE + 10
#define QUEUE_PERMISSIONS 0660
static pthread_t rxHdlr;
static pthread_t txHdlr;
static void* Transmit(void* arg);
static void* Receive(void* arg);
char readBuffer [MSG_BUFF_SIZE];
char writeBuffer [MSG_BUFF_SIZE];
#define NAME "/sp-sample"
int main(int argc, char* argv[])
{
if (pthread_create(&rxHdlr, NULL, Receive, NULL) != 0)
{
printf("Fail to create a server thread!\n");
}
if (pthread_create(&txHdlr, NULL, Transmit, NULL) != 0)
{
printf ("fail to create a client thread\n");
}
pthread_join(rxHdlr, 0);
pthread_join(txHdlr, 0);
}
Consumer
static void* Receive(void* arg)
{
struct mq_attr attr;
static mqd_t mqd;
attr.mq_flags = 0;
attr.mq_maxmsg = MAX_MESSAGES;
attr.mq_msgsize = MAX_BUFF_SIZE;
attr.mq_curmsgs = 0;
mq_unlink(NAME);
if ((mqd = mq_open (NAME, O_RDONLY | O_CREAT, 0644, &attr)) == -1)
{
printf ("mq_open failed in UartRx: %s\n", strerror(errno));
exit (1);
}
while(1)
{
int iret = mq_receive(mqd, readBuffer, sizeof(readBuffer), NULL);
if (iret == -1)
{
printf ("Errno: %d\n", errno);
}
printf ("Received buffer: %s\n", readBuffer);
}
}
Producer
static void* Transmit(void* arg)
{
int iRet;
mqd_t mqd;
char buffer[100] = "TX data!";
if ((mqd = mq_open (NAME, O_WRONLY)) == -1)
{
printf ("TX MqOpen failed - %s\n", strerror(errno));
exit (1);
}
while(1)
{
if (mq_send (mqd, buffer, strlen (buffer) + 1, 0) == -1)
{
perror ("Client unable to send message to server");
}
printf ("Sent...\n");
}
}