Lpc2000

hi all,
i am trying to boost the PRocessor clock to near full speed by 
setting the PLL registers
but PLL is not locking .
 am i making any mistake in configuring the PLL 
here is my pll setting code 

void SetPLLtoMaxSpeed()
{


  // set PLL multiplier & divisor.
  // values computed from config.h
 REG(SYSCON_PLLCFG)= 0x23;			    //where 
	M=4,P=2, fosc=14.7456MHz,Fcclk=58.98MHz
 REG(SYSCON_PLLFEED) = 0xAA;                      
 REG(SYSCON_PLLFEED) = 0x55; 
   
  // enable PLL
  REG(SYSCON_PLLCON)  = 0x01;
  REG(SYSCON_PLLFEED) = 0xAA;
  REG(SYSCON_PLLFEED) = 0x55;

    // wait for PLL lock
  while (!(REG(SYSCON_PLLSTAT) & 0x0400))           
    continue;

  // enable & connect PLL
  REG(SYSCON_PLLCON) = 0x03;
  REG(SYSCON_PLLFEED)  = 0xAA;
  REG(SYSCON_PLLFEED) = 0x55;

  // setup & enable the MAM
 //MAMTIM = MAMTIM_CYCLES;
 // MAMCR = MAMCR_FULL;

  // set the peripheral bus speed
  // value computed from config.h
  REG(SYSCON_VPBDIV)  = 0x02;                // set the peripheral 
bus clock speed to processor clock

}

thanks

shridhar