Redmine

Hi Team

when i am running the command "rake generate_secret_token" in the redmine directory its showing an error like this

rake aborted!
/usr/local/lib/ruby/1.8/x86_64-linux/digest/sha1.so: undefined symbol: rb_Digest_SHA1_Init - /usr/local/lib/ruby/1.8/x86_64-linux/digest/sha1.so

(See full trace by running task with --trace)

my ruby version is

ruby 1.8.7 (2008-05-31 patchlevel 0) [x86_64-linux]

and am using Debian GNU/Linux 6.0 \n \l
Issue
Please help me