panel count function will raise TypeError when the value of dataframe  is None
import pandas as pd
import numpy as np
df1=pd.DataFrame(index=range(8),columns=['a','b','c']) #a empty dataframe
df1.ix[:]=None  #assign NULL
panel1=pd.Panel(dict(df1=df1))
df1.count()   #good
panel1.count()    #raise exception now
the exception is rasied,it says,TypeError: ufunc 'isfinite' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''
how to repair it?any replies will be appreciated,thank you
