debian 6 安装aptitude问题

~$ sudo apt-get install aptitude 完成后运行出现以下错误

~$ sudo aptitude update
aptitude: error while loading shared libraries: libept.so.1.aptpkg4.12: cannot open shared object file: No such file or directory

~$ ldd /usr/bin/aptitude
linux-vdso.so.1 (0x00007ffff8bff000)
libapt-pkg.so.4.12 => /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12 (0x00007f1ef18bd000)
libncursesw.so.5 => /lib/libncursesw.so.5 (0x00007f1ef166a000)
libtinfo.so.5 => /lib/x86_64-linux-gnu/libtinfo.so.5 (0x00007f1ef1440000)
libsigc-2.0.so.0 => /usr/lib/libsigc-2.0.so.0 (0x00007f1ef123b000)
libcwidget.so.3 => /usr/lib/libcwidget.so.3 (0x00007f1ef0f6f000)
libept.so.1.aptpkg4.12 => not found
libxapian.so.22 => /usr/lib/libxapian.so.22 (0x00007f1ef0b8e000)
libz.so.1 => /usr/lib/libz.so.1 (0x00007f1ef0977000)
libsqlite3.so.0 => /usr/lib/libsqlite3.so.0 (0x00007f1ef06df000)
libboost_iostreams.so.1.54.0 => not found
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f1ef04c2000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f1ef01be000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f1eefebb000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f1eefca5000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f1eef8fa000)
libutil.so.1 => /lib/x86_64-linux-gnu/libutil.so.1 (0x00007f1eef6f7000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f1eef4f3000)
libbz2.so.1.0 => /lib/libbz2.so.1.0 (0x00007f1eef2e2000)
libuuid.so.1 => /lib/libuuid.so.1 (0x00007f1eef0de000)
/lib64/ld-linux-x86-64.so.2 (0x00007f1ef2229000)