Mutilple Vehicle Type

Dear all,
I have a problem with setting different types of vehicle in Jsprit.
The result shows that Jsprit only recognizes the vantype, but not biketype in my problem. It means the results only contain the type of van, and unassigned jobs, even though there are 5 bikes available.
I did a test. If I delete the setting of van, the results will return all the jobs as unassigned job, but the 5 bikes are never used by Jsprit in my problem.
When I print the vehicletype added into the vrpBuilder, it shows both van and bike type are available.
So it is quite strange, and I am struggling to fix this issue.

The following is my impletation:

    VehicleType vantype = VehicleTypeImpl.Builder.newInstance("vantype").addCapacityDimension(0, 70).setCostPerDistance(10).setFixedCost(5).build();
    VehicleType biketype = VehicleTypeImpl.Builder.newInstance("biketype").addCapacityDimension(0, 70).setCostPerDistance(2).setFixedCost(2).build();
        int vanCount = 15;
	    for (int i = 0; i < vanCount; i++) {
	    	VehicleImpl van = VehicleImpl.Builder.newInstance("van" + i).setStartLocation(Location.Builder.newInstance().
    int bikeCount = 5;
    for (int i = 0; i < bikeCount; i++) {
    	VehicleImpl bike = VehicleImpl.Builder.newInstance("bike" + i).setStartLocation(Location.Builder.newInstance().