PADS导入allegro时出错，怎么会事啊？

Translating D:\PADS2005\2005\Samples\SBPnetlist.asc.
Reading PADS ASCII file header.
 Version = PowerPCB3.0
PARSE ERROR: Unable to find the *PCB* section of the input file.
Line 407: *END*     OF ASCII OUTPUT FILE
Finished with errors！