The program is failing in the kartrisclasses.vb code atline 545 on this line lstShippingOptions =clsPlugin.GetRates(Payment.Serialize(objShippingDetails))
 
here is the error log below. 
>>    12/17/2012 8:38:14 PM
>>     ::1
>>    DESCRIPTION:
Conversion from string "" to type 'Integer' isnot valid.
 
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Earlier this year, I had this same problem with USPS integration and now I am getting the same with UPS. Can someone please check the dll for the latest version?