Date picker can't display well when on click

When click on the date picker, it sometimes flash but did not popup. It seem showed but immediately close down. Would like to know how to solve this.

/*html*/
```

/*jquery*/
$(document).ready(function() {
/*date picker*/
/*from date*/
var from_$input = $('#fromDate').pickadate(),
from_picker = from_$input.pickadate('picker')

/*to date*/
var to_$input = $('#toDate').pickadate(),
to_picker = to_$input.pickadate('picker')

// Check if there’s a “from” or “to” date to start with.
if ( from_picker.get('value') ) {
to_picker.set('min', from_picker.get('select'))
}
if ( to_picker.get('value') ) {
from_picker.set('max', to_picker.get('select'))
}

// When something is selected, update the “from” and “to” limits.
from_picker.on('set', function(event) {
if ( event.select ) {
to_picker.set('min', from_picker.get('select'))
}
else if ( 'clear' in event ) {
to_picker.set('min', false)
}
})
to_picker.on('set', function(event) {
if ( event.select ) {
from_picker.set('max', to_picker.get('select'))
}
else if ( 'clear' in event ) {
from_picker.set('max', false)
}
})

});

function getTime(value){
if (value == 'start') {
currentStart = $('#fromDate').val() +' 00:00:00';
}else if(value == 'end') {
currentEnd = $('#toDate').val() +' 23:59:59';
}

}