ExactTarget Landing Page form - some submitted values not being passed in Ampscript

I have created an ExactTarget Landing Page form which does two things upon submission.

1. Create a Lead
2. Create a Campaign Response - *this part works with no issues

The relevant AMPScript is below.

What is happening is this - if I remove the two 'Opt-Out' fields(3rd and 4th from the bottom) from the Object creation, the 'Description' and 'Lead Source' fields right below it populate SFDC with no issues.

However, if I put the Opt-Out fields back in, both the 'Description' and 'Lead Source' fields don't populate in SFDC, even though I can see them in the posted form values.

Is there anything that looks incorrect? If I had any hair I'd be pulling it out.

---

** Below will set the 'OPT-OUT' values but NOT pass the 'Description' and 'LeadSource'

SET @_SFobjid = CreateSalesforceObject
("Lead",13,"Company",RequestParameter("Company"),
"StateCode",RequestParameter("StateCode"),
"PostalCode",RequestParameter("PostalCode"),
"HasOptedOutOfEmail",IsNullDefault(RequestParameter("HasOptedOutOfEmail"),"False"),
"Mail_Opt_Out__c",IsNullDefault(RequestParameter("Mail_Opt_Out__c"),"False"),
"Description",@Description,
"LeadSource",RequestParameter("LeadSource"))

** Below will pass the 'Description' and 'LeadSource' with the Opt-Out fields not included

SET @_SFobjid = CreateSalesforceObject
("Lead",13,"Company",RequestParameter("Company"),
"StateCode",RequestParameter("StateCode"),
"PostalCode",RequestParameter("PostalCode"),
"Description",@Description,
"LeadSource",RequestParameter("LeadSource"))

Attribution to: Brian M
This content is remixed from stackoverflow or stackexchange. Please visit https://salesforce.stackexchange.com/questions/34562