DC - edifout gives warning "designs have no schematic&q

Was using DC to write out an edif file.
An error (EDFO-1) states: some designs have no schematic.

What does it mean? how do i solve this problem?

DC - edifout gives warning "designs have no schematic&a

EDFO-1 (warning) Some designs have no schematic.
DESCRIPTION
The variable edifout_netlist_only is set to false, and you executed the edif format
write command. But for some of the designs that you want to write, no schematics
have been created.
WHAT NEXT
If you want to write the designs without including schematic descriptions, set the
variable edifout_netlist_only to true. Then execute the edif format write command
again.
If you want to write the designs including schematic descriptions, execute the
create_schematics command. Then execute the edif format write command again. If
you’re going to execute the edif format write command with the -hierarchy option,
then be sure to also execute the create_schematics command with the -hierarchy
option.