1 I cant read many stocks(list) with pandas-datareader from yahoo

[Davidii111]

import pandas_datareader as pdr
import datetime 
import pandas as pd

largecap = pd.read_excel('largecap.xlsx')
antalrader = len(largecap.index)

stocks = list()

x = 0
while x < antalrader:
   stocks.insert(x, largecap.Yahoo[x])
   x += 1


print(type(stocks[121]))
ls_key = 'Adj Close'
start = datetime.datetime(2016, 1, 1)
end = datetime.datetime(2016, 1, 31)   
f = pdr.DataReader(stocks, 'yahoo', start, end)
print(f)

Error message:

/Users/david.soderstrom/anaconda3/lib/python3.6/site-packages/pandas_datareader/yahoo/daily.py:136: SymbolWarning: Failed to read symbol: 'AHSL.ST', replacing with NaN.
 warnings.warn(msg.format(sym), SymbolWarning)

Why can't i read the symbols from yahoo? I have 122 values in the list. If i write:

pdr.DataReader(AHSL.ST, 'yahoo', start, end)

It does read correctly from yahoo.

[nilamo]

The only thing I can think of is that there's some character you can't see there, like a unicode space or something.  What do you see if you do: print([ord(ch) for ch in stocks[121]])?