Changing Key for all Sectors in RFID Card error using "for"

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Hi Guys i am using a arduino uno and MFRC522 to read and write from and to a card

but when i want to change the key i need to specify a specific sector so i used the

'for' Command and i get a PCD_authentication failed

the small piece of code where i get error is

    for (int i = 1; i < 16; i++){ // 16  is to encrypt all sectors which are 15 including 0 
         if (!MIFARE_SetKeys(&key, &key, &newKeyA, &newKeyB, i)) {
    Serial.print("Block Not Encrypted: ");
    Serial.print(i);
    Serial.println();
  }
  }

i do not want to encrypt sector 0 as it has its own unique key

how do i solve this