convert char A[] to double

Question

I have an arduino code that inputs volume in a char datatype, I want to convert it to double, Ive tried using atof but it wont work. Whats the problem from my code. Sorry Newbie here!!

double v;
int data_count = 0;
int i;
char Data[16];
char volume[16];
char inputTime[16];

// Define the Keymap for Keypad
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'.', '0', '#', 'D'}
};
lcd.setCursor(0, 0);
  lcd.print("Input Volume:");

  if (customKey != NO_KEY && customKey != '#'
      && customKey != 'A' && customKey != 'B' && customKey != 'C'
      && customKey != 'D') {
    Data[data_count] = customKey;
    lcd.setCursor(data_count, 1);
    lcd.print(Data[data_count]);
    data_count++;
  }

  if (customKey == '#') {
    volumelength = data_count;
    for (i = 0; i < volumelength; i++) {
      volume[i] = Data[i];          
    }
    clearData();
    nextstate();
    data_count = 0;
    v = atof(volume);
  }