On workstations, NGDBuild does not recognize EDIF netlists that contain uppercase ".EDN" extensions. A typical reported error message refers to the file not being found or created, similar to the following:
"ERROR:basnb:48 - Top-level input design file "test.EDN" cannot be found or created. Please make sure the source file exists and is of a recognized netlist format (e.g., NGO, EDIF or XNF)."
The error might also refer to an "Unexpanded logical block." This problem is most often encountered when I attempt to port EDIF netlists created on a PC to a UNIX workstation.
NGDBuild is case-sensitive for both file name roots and extensions on workstation platforms. To avoid these errors, you must rename the file with a lowercase ".edn" extension.