I run code in research jupyter notebook:

minutes=len(df_price)
ema = qb.Indicator(ExponentialMovingAverage(750), syl, minutes, Resolution.Minute)
close = qb.Indicator(SimpleMovingAverage(1), syl, minutes, Resolution.Minute)
close = close.drop('simplemovingaverage', axis = 1)
close_over_ema = IndicatorExtensions.Over(close, ema)

the output is :

InvalidCastException: cannot convert object to target type
  at Python.Runtime.PyObject.AsManagedObject (System.Type t) [0x00011] in <5699e871b2d343059e1ba5b428b465a0>:0 
  at QuantConnect.Indicators.IndicatorExtensions.Over (Python.Runtime.PyObject left, Python.Runtime.PyObject right, System.String name) [0x00008] in <03b550573bc44002ba53a1f597f9e9c4>:0 
  at (wrapper managed-to-native) System.Reflection.MonoMethod.InternalInvoke(System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00032] in <b0e1ad7573a24fd5a9f2af9595e677e7>:0 

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