这是什么原因

Warning (20028): Parallel compilation is not licensed and has been disabled
Warning (12019): Can't analyze file -- file Vhdl1.vhd is missing
Error (12007): Top-level design entity "vhdl" is undefined
Error: Quartus II 32-bit Analysis & Synthesis was unsuccessful. 1 error, 2 warnings
        Error: Peak virtual memory: 264 megabytes
        Error: Processing ended: Wed Mar 07 14:27:47 2012
        Error: Elapsed time: 00:00:05
        Error: Total CPU time (on all processors): 00:00:03