Chart Y-axis goes mad when values are big

[villeseppala]

I have problem with all my charts (bar,line,column). When I'm showing some data with small values (less than 4million) everything looks good. But when my data changes and some values are really big (800million) the y-axis goes insane.
27665
(5.10 value is 819710368.82)

myChart

Ext.create('Ext.chart.Chart', {
store : 'myStore',
animate : true,
shadow : true,
theme : 'Base',
axes : [
{
type : 'Numeric',
position : 'left',
fields : ['line1', 'line2'],
grid : true
},
{
type : 'Category',
position : 'bottom',
fields : ['ntie']
}
],
series: [
{
title : 'title1',
type : 'line',
axis : 'left',
highlight : true,
fill : true,
xField : 'ntie',
yField : 'kytt'
},
{
title : 'title2',
type : 'line',
axis : 'left',
highlight : true,
fill : true,
xField : 'ntie',
yField : 'kvvv'
}
}
});

Thanks in advance.