Why I am getting Notice: Undefined index: CIRReportData JSON PHP

  <?php
  $response = '{
"CCRResponse": {
    "Status": "1",
    "CIRReportDataLst": [
        {
            "CIRReportData": {
                "IDAndContactInfo": {
                    "PersonalInfo": {
                        "Name": {
                            "FullName": "URMILA GUPTA ",
                            "FirstName": "URMILA ",
                            "LastName": "GUPTA "
                        },
                        " AliasName": {},
                        "DateOfBirth": "1951-11-05"
                    }
                }
            }
        }
    ]
}
    }';
   $r1 = json_encode(json_decode($response), JSON_PRETTY_PRINT);
  $obj = json_decode($response, true);
     foreach ($obj["CCRResponse"]["CIRReportDataLst"] as $key) {
     echo $fullname = $key["CIRReportData"]["IDAndContactInfo"]["PersonalInfo"]["Name"] 
   ["FullName"];
        }?>

Can any help me why I am getting Notice: Undefined index: CIRReportData error?
I am able to get a response from my code but still getting errors.
I want
Kindly help me.