Trailhead Superbadge- lightning component framework specialist : Challenge 2

I am stuck in challenge 2. Functionality is working as expected. But I get error as - Challenge Not yet complete... here's what's wrong:
The BoatSearch component should instantiate the BoatSearchForm and BoatSearchResults components.
Below is my BoatSearch component.

<aura:component implements="force:appHostable,flexipage:availableForAllPageTypes" access="global" >
    <lightning:card title="Find a Boat"  class="slds-m-top_10px">
        <c.BoatSearchForm/>
    </lightning:card>
    <lightning:card title="Matching Boats">
        <c.BoatSearchResults/>
    </lightning:card>
</aura:component>

Any lead is appreciated.
Thanks,
Manish