I'm writing my first algorithm and I'm trying to modify the result of the pipeline tutorial to select stocks to long/short based on an ExponentialWeightedMovingAverage (EWMA) crossover. But for some reason, it's as if the main criteria gets completely ignored or flipped. Here's a snippet of my code:

def make_pipeline():  
...
# Find stocks that are trending up or down  
    ewma_10 = ExponentialWeightedMovingAverage(inputs=[USEquityPricing.close], window_length=10, decay_rate=0.94, mask=base_universe)  
    ewma_30 = ExponentialWeightedMovingAverage(inputs=[USEquityPricing.close], window_length=30, decay_rate=0.94, mask=base_universe)  
    percent_difference = (ewma_10 - ewma_30) / ewma_30  
    # Create filters to select securities to short and long.  
    trending_up = ewma_10 > ewma_30  
    trending_down = ewma_10 < ewma_30  
    longs = trending_up & True  # force convert to boolean  
    shorts = trending_down & True

    securities_to_trade = (shorts | longs)

    pipe = Pipeline(  
        screen = securities_to_trade,  
        columns = {  
            'dollar_volume': dollar_volume,  
            '10_day_ewma_close': ewma_10,  
            '30_day_ewma_close': ewma_30,  
            'latest_close_price': latest_close,  
            'percent_difference': percent_difference,  
            'longs': longs,  
            'shorts': shorts  
        }  
    )  
    return pipe  

And an example output of a stock that gets bought long is this:

2016-01-04 05:45 my_assign_weights:181 INFO 589 longs: ABMD, TAP, ADBE, ADM...
2016-01-04 05:45 PRINT Equity(53 [ABMD])
2016-01-04 05:45 PRINT dollar_volume = 3890037027.53
2016-01-04 05:45 PRINT 10_day_ewma_close = 107.355376287
2016-01-04 05:45 PRINT 30_day_ewma_close = 111.151362922
2016-01-04 05:45 PRINT latest_close_price = 105.23
2016-01-04 05:45 PRINT percent_difference = -0.0341515077781

As you can see, 10_day_ewma_close is not greater than 30_day_ewma_close, as I had specified. What am I doing wrong? Why is the filter doing the exact opposite of what I'm intending to do? Thanks ahead for any help!