Problems with equalsIgnoreCase?

Problems with equalsIgnoreCase?

Hello,
I am attempting to revive an App used last year for this coming summer. I have run into an issue with my registration validation and case sensitivity. The equalsIgnoreCase() function does not seem to catch case variations with my entries. Is this something others are experiencing? Thank you for any insight you can share!

I check a new entry against my existing entries to ensure a new user does not share a First Name, a Last Name, AND a Phone Number. Here is the code I am using:

temp = input.Phone_Number.getAlphaNumeric() ; 
temp = temp.removeAllAlpha() ; 
if ( temp.length() == 10 )  
{
     temp = temp.subString(0,3) + "-" + temp.subString(3,6) + "-" + temp.subString(6,10) ; 
     if ( Add_SLP_Participants[Last_Name.equalsIgnoreCase(input.Last_Name) && First_Name.equalsIgnoreCase(input.First_Name) && Phone_Number == temp].count() > 0 )  
     {
        openUrl("#Form:Alert?status=dup&Last=" + input.Last_Name + "&First=" + input.First_Name + "&Phone=" + temp,"Popup window") ; 
     }
}