public class ContactAndLeadSearch {

    public static List<List<SObject>> searchContactsAndLeads( String nome)
    {   
        List<List<sObject>> searchList = [FIND :nome IN All Fields RETURNING Contact(FirstName,LastName),Lead(FirstName,LastName)];
        return searchList;         
    }
}

Hi all, 
I'm a newby in Salesforce so I decided to start learning with the Trailhead. 
I have completed all the challanghes related to the "Getting Started with the Force.com Platform". 
This morning I started with the part 2: "Intro to Visual App Development". 

The fist challenge for Workflow Atuomation is about "Automated Process with Workflow". 
I did the challenge but I receive a failure even if It should seems to run correctly in my Develper Edition Platform. 
Tha error massage received by the check challange button is "Challenge not yet complete... here's what's wrong: Case escalation failed to assign a task to the owner."

I say that all seems to work fine because I edited e case, set up the Priority to High and: 
1) The Escaleted flag was set automatically to true as per the rule action defined
2) I receive a notification about escalation on that case (because I'm the owner of the case as per the task definition field)
3) An activity under the case was automatically created and assigne to me. 

As anyone tha same problem?
Any help would be much appreciated. 
Thank's in advance,
Alvaro.