What is causing this Error? 

An error stating "Parsing Error" indicates that the headers on the comma-delimited value (.CSV) file do not match what Lighthouse Transaction Manager (LTM) Periodic Billing expects. This may also be due to the document not being in a text (.txt) format. 

How do I resolve this Error?

Confirm you follow the guidelines for importing a comma-delimited file into Periodic Billing, and ensure that the file extension is correct for importing into LTM.