When setting fabric for edge sewing, the fabric edge indicator line does not appear on the LCD screen / the Fabric edge indicator line doesn't align with the edge of the fabric / the "Distance from edge of fabric" indication doesn't stabilize.

The machine stops and displays error message "Fabric edge is not recognized at this point" while edge sewing though the stitching is not reaching near the edge of the fabric.

Can I use twin needle with edge sewing?

The "Fabric Seam Allowance" distance indication changes when lowering the presser foot after positioning the fabric in edge sewing function.

Despite selecting an edge sewing-compliant pattern, edge-sewing key appears in grey and cannot be selected.  

Though touching "OK" on "Attach vertical stitch alignment foot and edge sewing sheet" window, the same window still appears.  

How do I place edge sewing sheet?