Holding Field id names in an array

Hi All,

I need to set some fields on a record after sending a email from a custom record, after the email is sent I want to capture the date and that it has been sent in a checkbox.  Have done this millions of times with single fields but in the case I have a FOR loop to loop through 2 email addresses and send the email to each one independently then capture that has been sent i.e Sent 1, Sent 2.

I have tried to create an array to store the field id's FieldArray1 = Sent 1 field name, Sent 2 field name & FieldArray2 = Sent On 1 field name, Sent On 2 field name.  These array position are then accessed during the FOR loop in the nlapiSetFieldValue, all works ok no errors and the emails get sent but the fields are not being updated on the record.