Error Calculating EMA

[Z]

Hello,

I have an issue when calculating the EMA for all my stocks, but not when only calculating some. Here is the code:

class MovingAverageCrossover(bt.Strategy):
    params = (
        ('ma_short_length', 50),
        ('ma_long_length', 200),
    )

    def __init__(self):
        for data in self.datas:
            data.ma_short = btind.ExponentialMovingAverage(data.close, period=self.params.ma_short_length)
            data.ma_long = btind.ExponentialMovingAverage(data.close, period=self.params.ma_long_length)

The error is occurring during cerebro.run, but it is related to the EMA... Here is the error:

Traceback (most recent call last):
  File "c:\Users\Z\Desktop\Python\Backtest\main.py", line 15, in <module>
    results = cerebro.run()
              ^^^^^^^^^^^^^
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\cerebro.py", line 1132, in run
    runstrat = self.runstrategies(iterstrat)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\cerebro.py", line 1298, in runstrategies
    self._runonce(runstrats)
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\cerebro.py", line 1657, in _runonce
    strat._once()
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\lineiterator.py", line 297, in _once
    indicator._once()
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\lineiterator.py", line 297, in _once
    indicator._once()
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\lineiterator.py", line 317, in _once
    self.oncestart(self._minperiod - 1, self._minperiod)
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\indicators\basicops.py", line 401, in oncestart
    super(ExponentialSmoothing, self).once(start, end)
  File "C:\Users\Z\AppData\Local\Programs\Python\Python311\Lib\site-packages\backtrader\indicators\basicops.py", line 364, in once
    dst[i] = math.fsum(src[i - period + 1:i + 1]) / period
    ~~~^^^
IndexError: array assignment index out of range

We get through the init method, but never get the prenext or next methods. I am clueless. Thanks for any help!