Does anyone have any idea as to why my OnClick Javascript button will work in every browser except IE. I receive an error saying: "A problem with the OnClick Javascript for this button or link was encountered: Expected ')' "

The code is below:
 

if("{!Lead.DT_App_Fee_Paid__c }" == '' || "{!Lead.Enrollment_Agreement_Signed__c }" == ''){ 
alert("REMINDER: Please populate the following field(s): App Fee Paid and Enrollment Agreement Paid") 
} 

else {window.open('/a0M/e?retURL={!Lead.Id}&Name={!Lead.Name}&00N1500000Fu4CN={!Lead.Phone}&00N1500000Fu4DB={!Lead.Email}&00N1500000Fu4Dz={!Lead.Enrollment_Agreement_Signed__c}&00N1500000Fu4DL={!Lead.LeadSource}&00N1500000Fu4C8=Enrolled&00N1500000Fu4DQ={!Lead.Program_Recruit_c__c}&00N1500000Fu4Df={!Lead.DT_App_Submitted__c}&00N1500000Fu4Dk={!Lead.DT_App_Fee_Paid__c}&CF00N1500000FuCSY={!Lead.DT_First_Contacted_User__c}&00N1500000FuCSd={!Lead.DT_First_Contacted__c}&00N1500000FuCSi={!Lead.DT_Tour_Booked__c}&00N1500000FuCSn={!Lead.Date_of_Tour__c}&CF00N1500000FuCSs={!Lead.DT_Tour_Complete_User__c}&00N1500000FuCSx={!Lead.DT_Tour_Complete__c}&00N1500000FuCT2={!Lead.FA_Appt_Date__c}&CF00N1500000FuCT7={!Lead.DT_FA_Appointment_Complete_User__c}&CF00N1500000FuCUF={!Lead.DT_App_Fee_Paid_User__c}&00N1500000HCbao={!Lead.Street}&00N1500000HCbat={!Lead.City}&00N1500000HCd3m={!Lead.State}&00N1500000HCbo7={!Lead.PostalCode}&00N1500000HCbb8={!Lead.Country}'); 

{!REQUIRESCRIPT("/soap/ajax/29.0/connection.js")} 
var c = new sforce.SObject("Lead"); 
c.id = "{!Lead.Id}"; 
c.Status = "Enrolled"; 
result = sforce.connection.update([c]); 
window.location.reload(); 
}