Fapi_setActiveFlashBank returns Fapi_Error_InvalidHclkValue

Hello, I try to use flash api for C28x in a F28M35H52C1 device.

this is my code:

Bool PreparaFlash()
{
	FlashGainPump();

	//vedi "flash_c28.c"
	//139-143
	EALLOW;
	FlashEccRegs.ECC_ENABLE.bit.ENABLE = 0;//***************************** NON HO CAPITO, DEVO VERAMENTE AZZERARE ???
	EDIS;

	//vedi "flash_c28.c"
	//150-151
	Fapi_StatusType oReturnCheck = Fapi_initializeAPI(F021_CPU0_BASE_ADDRESS, 150);
	if(oReturnCheck!=Fapi_Status_Success) return(FALSE);

	//vedi "flash_c28.c"
	//174-175
	oReturnCheck = Fapi_setActiveFlashBank(Fapi_FlashBank0);
	if(oReturnCheck != Fapi_Status_Success) return(FALSE);

	return(TRUE);
}

when I call Fapi_setActiveFlashBank I get Fapi_Error_InvalidHclkValue.

I read spnu510e.pdf for Fapi_setActiveFlashBank but it says two return values:  Fapi_Status_Success or Fapi_Error_InvalidBank and I not understand.