Not able to update null value using rforcecom update function in RForcecom package

[ghareesh]

Hi,
I am struggling to update null values back to some date fields using rforcecom.update function.

Code snippet where issue comes:
for(my_index in 1:nrow(test)) {
objectName= "Case_Extension__c"
id <- paste("",test$Id[my_index],"", sep = "")
fields <- c(Quote_Validity__date =test$Quote_Validity__date[my_index])
rforcecom.update(session, objectName, id, fields) }
}

This perfectly works except for instances where Quote_Validity__date is NA. When NA, it shows following error..
Error in rforcecom.update(session, objectName, id, fields) : XML_PARSER_ERROR: 'NA' is not a valid value for the type xsd:date

While using rforcecom.createBulkBatch method , this was smooth. But we cannot continue using bulk updates due to salesforce restrictions for number of bulk operations per day. Is there a way, we can update null values with rforcecom.update function.. This will hugely help..