Error when building crosstool-ng-1.17.0

When i am trying to build crosstool-ng-1.17.0 using ct-ng build i am getting the below error please help me to resolve this issue. Thanks in Advance.

shiny@ubuntu:~/crosstool-ng-1.17.0$ ct-ng build
[INFO ] Performing some trivial sanity checks
[INFO ] Build started 20130111.120042
[INFO ] Building environment variables
[INFO ] =================================================================
[INFO ] Retrieving needed toolchain components' tarballs
[ERROR]
[ERROR] >>
[ERROR] >> Build failed in step 'Retrieving needed toolchain components' tarballs'
[ERROR] >> called in step '(top-level)'
[ERROR] >>
[ERROR] >> Error happened in: do_cloog_get[scripts/build/companion_libs/cloog.sh@728]
[ERROR] >> called from: main[scripts/crosstool-NG.sh@543]
[ERROR] >>
[ERROR] >> For more info on this error, look at the file: 'build.log'
[ERROR] >> There is a list of known issues, some with workarounds, in:
[ERROR] >> '/opt/crosstool-ng-1.17.0/share/doc/crosstool-ng/ct-ng.1.17.0/B - Known issues.txt'
[ERROR]
[ERROR] (elapsed: 1:38.73)
[01:39] / make: *** [build] Error 1