stm32l451 error when trying to write to the Flash

i am trying to implement openBootloader for an stm32l451,

but i cant get the write to work i get the following errors HAL_FLASH_ERROR_PROG | HAL_FLASH_ERROR_PGA |HAL_FLASH_ERROR_PGS

i am trying to write to 800c000 in the flash

this is my code( i used https://github.com/STMicroelectronics/stm32wl-openbl-apps to assist in how to write the interfaces)

void OPENBL_FLASH_Unlock(void) { HAL_FLASH_Unlock(); }

static void OPENBL_FLASH_Program(uint32_t Address, uint64_t Data) {
 /* Clear all FLASH errors flags before starting write operation */
 __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_ALL_ERRORS);

 HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, Address, Data);
}


void OPENBL_FLASH_Write(uint32_t Address, uint8_t *Data, uint32_t DataLength) { 
 uint32_t index;
 __ALIGNED(4) uint8_t buffer[FLASH_PROG_STEP_SIZE] = {0x0U};
 uint8_t remaining;

 if ((Data != NULL) && (DataLength != 0U)) {
 /* Unlock the flash memory for write operation */
 OPENBL_FLASH_Unlock();

 /* Program double-word by double-word (8 bytes) */
 while ((DataLength >> 3U) > 0U) {
 for (index = 0U; index < FLASH_PROG_STEP_SIZE; index++) {
 buffer[index] = *(Data + index);
 }

 OPENBL_FLASH_Program(Address,
 *((uint64_t *)buffer));

 Address += FLASH_PROG_STEP_SIZE;
 Data += FLASH_PROG_STEP_SIZE;
 DataLength -= FLASH_PROG_STEP_SIZE;
 }

 /* If remaining count, go back to fill the rest with 0xFF */
 if (DataLength > 0U) {
 remaining = FLASH_PROG_STEP_SIZE - DataLength;

 /* Copy the remaining bytes */
 for (index = 0U; index < DataLength; index++) {
 buffer[index] = *(Data + index);
 }

 /* Fill the upper bytes with 0xFF */
 for (index = 0U; index < remaining; index++) {
 buffer[index + DataLength] = 0xFFU;
 }

 /* FLASH word program */
 OPENBL_FLASH_Program(Address,
 (uint64_t)(*((uint64_t *)((uint32_t)buffer))));
 }

 /* Lock the Flash to disable the flash control register access */
 OPENBL_FLASH_Lock();
 }

 is where something i am missing ?