I am unsure why the following code does not work and gives me the following error [duplicate]

This question already has an answer here:

• Pandas conditional creation of a series/dataframe column 6 answers
• Truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all() 4 answers

I am trying to run through the dataframe and create a new column whose values are dependent on an if statement.

I have googled the error and read some answers but it does not make sense to me as to why it is not working

for i in fb:
     if fb['MA10'] > fb['MA50']:
        fb['Shares'] = 1
     else: 
        fb['Shares'] = 0

fb.head(10)

here is the error I get:

>The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Open    High    Low Close   Adj Close   Volume  MA10    MA50    Shares

2015-03-13  22.559999   22.760000   22.250000   22.700001   22.116024   8982200 22.648  21.0174 0
2015-03-16  22.879999   23.110001   22.730000   22.969999   22.379078   5923900 22.685  21.0758 0
2015-03-17  22.920000   23.260000   22.760000   23.250000   22.651876   7497500 22.792  21.1382 0
2015-03-18  23.250000   23.370001   22.660000   22.870001   22.281652   10337600    22.836  21.1998 0
2015-03-19  22.950001   23.299999   22.780001   23.219999   22.622650   7768900 22.872  21.2804 0
2015-03-20  23.410000   23.610001   23.190001   23.469999   22.866215   11552100    22.964  21.3670 0
2015-03-23  22.770000   23.070000   22.700001   22.709999   22.125767   10595700    22.974  21.4240 0
2015-03-24  22.639999   22.799999   22.299999   22.400000   21.823744   8262000 22.914  21.4732 0
2015-03-25  22.389999   22.389999   20.969999   21.040001   20.498730   13563800    22.730  21.5002 0
2015-03-26  20.610001   21.059999   20.459999   20.969999   20.430529   7798000 2   2.560   21.5264 0

Here I have modified my code by inserting .any() here:

if fb['MA10'].any() > fb['MA50'].any():

but as you can see the issue becomes that I get zero's for all my 'Shares' column when I should not be.