Keil 7.5 + simulator.

I'm obviously doing something wrong here, but I've stared at it for ages, and I don't understand where this is going wrong.

I'm calling the function below with a value of TICK_MS = 10 (confirmed in the simulator). OSC_FREQ is 12000000UL. OSC_PER_INST is 12. As far as I can see this should give an Inc value of 10000 (which it does, again confirmed in the simulator) and a Reload_16 value of 55536 (0xD8F0), but I always get 0x0000 here instead. In fact, I seem to get 0x0000 here whatever value of TICK_MS I use. A little hint would be grand.

I'm willing to bet that it's something really stupid :).

Thanks in advance,

Rob.

/*-*------------------------------------------------------------------

   COPYRIGHT
   ---------

   This code is associated with the book:

   EMBEDDED C by Michael J. Pont 
   [Pearson Education, 2002: ISBN: 0-201-79523-X].

   This code is copyright (c) 2001 by Michael J. Pont.
 
   See book for copyright details and other information.

-*------------------------------------------------------------------*/


void sEOS_Init_Timer0(const tByte TICK_MS)
   {
   tLong Inc;
   tWord Reload_16;
  


   // Using Timer 0, 16-bit *** manual reload ***
   TMOD &= 0xF0; // Clear all T0 bits (T1 left unchanged)
   TMOD |= 0x01; // Set required T0 bits (T1 left unchanged) 

   // Number of timer increments required (max 65536)
   Inc = ((tLong)TICK_MS * (OSC_FREQ/1000)) / (tLong)OSC_PER_INST;   

   // 16-bit reload value
   Reload_16 = (tWord) (65536UL - Inc);
   

   // 8-bit reload values (High & Low)
   Reload_08H = (tByte)(Reload_16 / 256);
   Reload_08L = (tByte)(Reload_16 % 256);

   // Used for manually checking timing (in simulator)
   //P2 = Reload_08H;
   //P3 = Reload_08L;

   TL0  = Reload_08L; 
   TH0  = Reload_08H;

   // Timer 0 interrupt is enabled, and ISR will be called 
   // whenever the timer overflows.
   ET0 = 1;

   // Start Timer 0 running
   TR0 = 1;     

   // Globally enable interrupts
   EA = 1;            
   }