LTC4418 Power/Battery Selector

Hi,

I need for a project a battery/power selector. My device should run with two batteries and it should always use the battery with the lower capacity. And when I disconnect the battery which is supplying the device the power switch should switch to the other battery and the device should not turn off.

 

I found the LTC4418 and made my own schematic. I is running fine but when i disconnect the battery which is supplying the device the power switch needs 13ms to switch to the other battery. And this is to long for the device. It turns off and starts again. 

 

Is there something wrong in my schematic or isn't it possible to switch between the batteries in under 1ms?