I have added a List button on campaign members that execicutes a javascript and deletes all campaign members in the campaign 

I am Getting error-  

{faultcode:soapenv:Client,Falultstrinf:Unexpected Element

{urn:partner.soap.sforce.com} type during simple type deserializition'}

Here is my Code 

{!REQUIRESCRIPT('/soap/ajax/29.0/connection.js')}

var result = sforce.connection.query("select Id from CampaignMember where Campaign.Name = '{!Campaign.Name}' ");
var records = result.getArray("records");


 var opt = confirm("Are you sure you want to delete selected records ?");
    if (opt == true) {
        var errors = [];
        var delresult = sforce.connection.deleteIds(records);
        if (result && result.length) {
            var numFailed = 0;
            var numSucceeded = 0;
            for (var i = 0; i < result.length; i++) {                 var res = result[i];                 if (res && res.success == 'true') {                     numSucceeded++;                 } else {                     var es = res.getArray("errors");                     if (es.length > 0) {
                        errors.push(es[0].message);
                    }
                    numFailed++;
                }
            }
            if (numFailed > 0) {
                alert("Failed: " + numFailed + "nSucceeded: " + numSucceeded + " n Due to: " + errors.join("n"));
            } else {
                alert("Number of records deleted: " + numSucceeded);
            }
        }
        window.location.reload();
    }