Time series graph, overlapping bars

Why the bars of my timeseries graph are overlapping?


here's my code..

var chart = c3.generate({
bindto: '#chart',
data: {
x: 'date',
xFormat: '%m/%d/%y %I:%M %p',
json: final_data,
keys: {
x: 'date',
value: values
},
type: 'bar',
groups: val
},
axis: {
x: {
type: 'timeseries',
tick: {
format: '%b %d',
centered: true,
fit: true
}
}
},
zoom: {
enabled: true
},
color: {
pattern: colors
}
});