what is the field type on the transaction field on your note record? currentInvoiceRec will return a number but I would also try stringing it ie String(currentInvoiceRec) depending what the transaction field can accept. Another thing you can also do is open dev tools in the browser to see if you can set the field with nlapiSetFieldValue in the console, or also open up the xml of an example of a note record by adding '&xml=T' to the end of the url. Futhermore, even though it takes more governance, I usually have a better time creating recording in a client script if i set isDynamic to true on the parameters for record.create