cannot erase the spi flash w25x32 in 6747

hello, every one ,i am debugging "spiflash.pjt" which is a example  provided by ti EVMC6747

The example project write, read and  erase the spi flash  w25x32 with SPI_SPIFMT0. Char Len=8bit,i want to modifiedit for read or write the flash for char len=16bit,but it cannot erase the flash ,  but i can  read the flash with char len=16bit,why?what is wrong ???please help me!

thank you!

the following is code:

======================

#include "spiflash.h"

static Uint16 spiflashbuf[spiflash_PAGESIZE/2 + 3];
static Uint32 spidat1;

void spiflash_init( )
{
     /* Reset SPI */
    SPI_SPIGCR0 = 0;
    EVMC6747_wait( 1000 );

    /* Release SPI */
    SPI_SPIGCR0 = 1;

    /* SPI 4-Pin Mode setup */
    SPI_SPIGCR1 = 0
        | ( 0 << 24 )
        | ( 0 << 16 )
        | ( 1 << 1 )
        | ( 1 << 0 );

    SPI_SPIPC0 = 0
        | ( 1 << 11 )   // DI
        | ( 1 << 10 )   // DO
        | ( 1 << 9 )    // CLK
        | ( 1 << 1 )    // EN1
        | ( 1 << 0 );   // EN0

    SPI_SPIFMT0 = 0
        | ( 0 << 20 )   // SHIFTDIR
        | ( 0 << 17 )   // Polarity
        | ( 1 << 16 )   // Phase
        | ( 2 << 8 )    // Prescale to 30MHz
        | ( 16 << 0 );   // Char Len

    spidat1 = 0
        | ( 1 << 28 )   // CSHOLD
        | ( 0 << 24 )   // Format [0]
        | ( 2 << 16 )   // CSNR   [only CS0 enbled]
        | ( 0 << 0 );   //

    SPI_SPIDAT1 = spidat1;

    SPI_SPIDELAY = 0
        | ( 8 << 24 )   // C2TDELAY
        | ( 8 << 16 );  // T2CDELAY

    SPI_SPIDEF = 0
        | ( 1 << 1 )    // EN1 inactive high
        | ( 1 << 0 );   // EN0 inactive high

    SPI_SPIINT = 0
        | ( 0 << 16 )   //
        | ( 0 << 8 )    //
        | ( 0 << 6 )    //
        | ( 1 << 4 );   //

    SPI_SPILVL = 0
        | ( 0 << 8 )    // EN0
        | ( 0 << 6 )    // EN0
        | ( 0 << 4 );   // EN0

    /* Enable SPI */
    SPI_SPIGCR1 |= ( 1 << 24 );
}

void spiflash_cycle(Uint16 *buf, Uint16 len)
{
  Uint16 i;
 SPI_SPIBUF;
 for (i = 0; i <len; i++)
 {
    while( SPI_SPIBUF & 0x10000000 );
  if (i == (len-1))
         SPI_SPIDAT1 = (spidat1 & 0x0ffcffff) |  buf[i] ;
  else
         SPI_SPIDAT1 = spidat1 | buf[i];
    while ( SPI_SPIBUF & ( 0x80000000 ) );
    buf[i] = SPI_SPIBUF;
 }
}

Uint8 spiflash_status( )
{
  spiflashbuf[0] = spiflash_CMD_RDSR<<8 | 0;
 spiflash_cycle(spiflashbuf, 1);
  return spiflashbuf[0];
}

void spiflash_sector_erase(Uint32 sector_num) 
{
 Uint32 eraseaddr=spiflash_SECTORSIZE*sector_num;

  spiflashbuf[0]=(spiflash_CMD_WREN<<8) | 0;
 spiflash_cycle(spiflashbuf, 1);

  spiflashbuf[0] = (Uint16) (spiflash_CMD_ERASESEC<<8)|(eraseaddr>>16);
 spiflashbuf[1] = (Uint16) (eraseaddr & 0xffff);
  spiflash_cycle(spiflashbuf, 2);

  while( ( spiflash_status( ) & 0x01) );
}

void main( void )

{
 Setup_System_Config( );       
 Setup_PLL();
 Setup_Psc_All_On( );          
 Setup_EMIFA();                 
 Setup_EMIFB();
  spiflash_init( );
 spiflash_sector_erase(0);    
}