Writing in flash is not working

Hi,

im new for Stm32. I want to write 4 numbers in the flash but always get an error message (status = HAL_ERROR while writing in flash). In my function I write the numbers in an array and want to write the individual elements into the flash.

The variables (zahlx) are uint8_t.

Can anyone tell me what I am doing wrong?

void save_to_flash(int wahl)
{
	volatile uint32_t write_cnt = 0, index = 0;
 
	volatile uint32_t data_to_FLASH[4];
 
	memset((uint8_t*)data_to_FLASH, 0,strlen((char*)data_to_FLASH));
 
 
	switch (wahl)
	{
	case 1:
		data_to_FLASH[0] = zahl1;
		data_to_FLASH[1] = zahl2;
		data_to_FLASH[2] = zahl3;
		data_to_FLASH[3] = zahl4;
		write_cnt = 0;
	break;
	case 2:
		data_to_FLASH[0] = zahl5;
		data_to_FLASH[1] = zahl6;
		data_to_FLASH[2] = zahl7;
		data_to_FLASH[3] = zahl8;
		write_cnt = 10;
 
	break;
	}
 
 
	HAL_FLASH_Unlock();			
 
	HAL_FLASH_OB_Unlock();
 
 
	FLASH_EraseInitTypeDef EraseInitStruct;	
	EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
	EraseInitStruct.Page = 127;
	EraseInitStruct.NbPages = 1;
	uint32_t PageError;
 
 
	volatile HAL_StatusTypeDef status;
	status = HAL_FLASHEx_Erase(&EraseInitStruct, &PageError);
 
	if(status == HAL_OK)
	{
		while(index < 4)
		{
		 status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD,FLASH_STORAGE+write_cnt, data_to_FLASH[index]);
			if(status == HAL_OK)		
 {			
				write_cnt +=4;	
 index++;	
			}
		}
	}
	HAL_FLASH_OB_Lock();
	HAL_FLASH_Lock();
 
}