MSP430FR5989: Failed to write data to address 0x10000 in FRAM

int ota_write(unsigned long offset,const unsigned char *pdata,unsigned int size)
{
    unsigned int i=0;
    for(i=0;i<size;i++)
    {
        __data20_write_char(offset+0x10000+i,pdata[i]);
    }

    for(i=0;i<size;i++)
    {
        if(__data20_read_char(offset+0x10000+i)!=pdata[i])
        {
            DBG_LOG("CHK ERR");  //Several random byte check failures
            return -1;
        }
    }

    return 0;
}
static unsigned char test_buf[20]={0};
void test_fram()
{
    int i=0,j=0;;
 
    for(i=0;i<55;i++)
    {
        for(j=0;j<sizeof(test_buf);j++)
        {
            test_buf[j]=j;
            check+=j; //fixed
        }
        if(ota_write(i*sizeof(test_buf),test_buf,sizeof(test_buf))!=0)

        {return ;}
    }


}