Require fails with undefined symbol

I have installed wxruby via gems on Ubuntu 7.10 but running
sample/minimal.rb fails:

ruby -rubygems minimal.rb

/var/lib/gems/1.8/gems/wxruby-1.9.8-x86-linux/lib/wxruby2.so:
/var/lib/gems/1.8/gems/wxruby-1.9.8-x86-linux/lib/wxruby2.so: undefined
symbol: g_assertion_message_expr -
/var/lib/gems/1.8/gems/wxruby-1.9.8-x86-linux/lib/wxruby2.so (LoadError)
from /usr/lib/ruby/1.8/rubygems/custom_require.rb:32:in
require' from /var/lib/gems/1.8/gems/wxruby-1.9.8-x86-linux/lib/wx.rb:12 from /usr/lib/ruby/1.8/rubygems/custom_require.rb:32:ingem_original_require’
from /usr/lib/ruby/1.8/rubygems/custom_require.rb:32:in
`require’
from minimal.rb:8

Any help (hopefully without recourse to source compilation) would be
very welcome.

Thanks, Richard W

Upgrading to Ubuntu 8.04 has cured the problem!