aix6.1下运行unzip报错

解压缩 oracle12C 文件，系统报错，请问这是为什么？谢谢了
unzip aix.ppc64_12102_database_1of2.zip
Archive:  aix.ppc64_12102_database_1of2.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of aix.ppc64_12102_database_1of2.zip or
        aix.ppc64_12102_database_1of2.zip.zip, and cannot find aix.ppc64_12102_database_1of2.zip.ZIP, period.