Pivottable (2 levels) NaN not showing

Question

I have a dataframe, which I create from another dataframe:

df_exp_fix = df_aus[df_aus['CATEGORY'] == "Fixkosten"] 

When I display df_exp_fix i get:

	MONTHYEAR	Comment	LEVEL2	LEVEL3	AMOUNT
0	01.01.2022	bla	Lebensmittel	Metro	10
1	01.02.2022	bla	Taschengeld	NaN	10

Next I do

table_exp_fix = df_exp_fix.pivot_table(values='AMOUNT', index=['LEVEL2', 'LEVEL3'], 
                               columns=['MONTHYEAR'], aggfunc=np.sum, margins=True)

But the Line "Taschengeld" is not displayed? And with that all Sums are not the same if I only aggregate on LEVEL2

I played around with dropna.... and other parameters but it doesn't get displayed

Any help?