Eruby dbi select problem

I’m using eruby/mod_ruby on Apache 2.2 and I’m having a problem doing a
select against a table (mysql 5)

sth = dbh.execute(“select type,site,amount from logger order by id

The select returns the results from type,site but not amount. Amount is
a decimal field. Ruby just throws the following internal server error.
If I remove amount it works fine. Any idea what I’m doing wrong?

[Mon Jan 21 12:19:14 2008] [error] mod_ruby:
/usr/lib/ruby/1.8/DBD/Mysql/Mysql.rb:649:in column_info': undefined method[]’ for nil:NilClass (NoMethodError)