Set fax setting to fine.
Check lens/other mechanics of fax machine for dirt, or other obstructions, such as white-out that may need to be cleaned.
Switch out phone cord (possible fraying).
Make sure that neither bar code on the fax cover sheet is faded, or has foreign markings on them.
Make sure that you have only faxed one document for each cover sheet. (This means 1 document and its system generated fax cover sheet per fax transmittal).
These are just a few things that may be the problem. If you have checked all of these steps and you still have issues, call the MLS Help Desk.