Discrepancies between charts/expressions

[QlickySense]

Hello,

I've got a pie chart with its numbers and % (used count and ticket relative option for one expression, for the other only count)

I wanted to change it to bar chart and highlight value (percentage)

My formula is 

DUAL(Num(count( {<MyVar1 *= {1}>} MyVar1),'#.') & ' (' & Num(count( {<MyVar1 *= {1}>} MyVar1)/count(TOTAL MyVar1 *= {1}>} MyVar1),'0.0%')&')',count( {<MyVar1 *= {1}>}MyVar1))

I can see slight discrepancies between charts in percentage

Pie chart (its accurate)

Cat1	3.3%	22
Cat2	6.2%	42
Cat3	16.7%	113
Cat4	16.0%	108
Cat5	57.8%	391

Bar chart

Cat1	22 (3.2%)
Cat2	42 (6.0%)
Cat3	113 (16.2%)
Cat4	108 (15.5%)
Cat5	391 (56.0%)

Looks like DUAL expression takes into consideration null values, because there is 3.2% for full values and when I add that, then its 100%.