the nonexistent data impact in stacked chart?

[guantujiang]

just in below data

ECC_DAte_BAse	FAmily	Sum
17.10.2014	A	3
	B	183
24.10.2014	C	20
	A	7
	B	193
31.10.2014	A	12
	B	1714
	D	158
7.11.2014	C	16
	A	94
	B	133
28.11.2014	C	85
	A	579
	B	1713

we can found that some family info is not in dates.

just like the 'D', not in 7.11.2014 and 28.11.2014

but look at the chart, even not data in 7.11.2014, the line still keep in it, what happen?

suppose it should like this

anyone can help ?

thanks

[guantujiang]

I found it work if the 'D' not in 1st position

like

[guantujiang]

anyone can help ?