SBUF Funny!!

This is a bit of funny one (see code below). Basically (1),(2),(3),(4),(5) and (6) all transmit their data successfully via SBUF. This was captured by Hyperterminal. However (7) only transmitted correctly when assignment to next state was made at (a) and not (b). The code below is commented in its non working state. Any thoughts?

This has happened in v7.0 and v7.5 of C-Compiler for C51. I have just upgraded compiler, but I can not believe it is the compiler what am I doing wrong?


Declarations in Global.h
//-------------------------------------------
extern unsigned char flag_DLE;
extern unsigned char next_state;
#define WAIT_FOR_START_SEQUENCE 0x00
#define WAIT_FOR_CHAR 0x01
#define STX 0x05
#define ETX 0x04
#define DLE 0x0F
//-------------------------------------------




Definition in main.c
//-------------------------------------------
unsigned char flag_DLE;
unsigned char next_state;
.
.
.
.
Code in void main()in main.c
//-------------------------------------------
(1) SBUF = STX;
Dly(10);
(b) next_state = WAIT_FOR_START_SEQUENCE;
(2) SBUF = STX;
Dly(10);
//(a) next_state = WAIT_FOR_START_SEQUENCE;
(7) SBUF = next_state;
Dly(10);
rcv_msg_pos = 0x00;
(3) SBUF = rcv_msg_pos;
Dly(10);
(4) SBUF = WAIT_FOR_START_SEQUENCE;;
Dly(10);
(5) SBUF = WAIT_FOR_CHAR;
Dly(10);
(6) SBUF = ETX;
Dly(10);
//-------------------------------------------