"Could not find a suitable archiver." using dorsal

I'm using Dorsal 0.7.2 on Snow Leopard 10.6.4 and the following is shown followed by an error concerning archiving. I am not familiar with build scripts! Where am I to specify an archiver and what does that even mean? Thank you so much!

=================================================================================
             Configuring PETSc to compile on your system
=================================================================================
/home_dir/cptr/Work/FEniCS/src/petsc-3.0.0-p12/config/BuildSystem/config/compilers.py:7: DeprecationWarning: the sets module is deprecated
  import sets
/home_dir/cptr/Work/FEniCS/src/petsc-3.0.0-p12/config/PETSc/package.py:7: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import md5
/home_dir/cptr/Work/FEniCS/src/petsc-3.0.0-p12/config/BuildSystem/script.py:101: DeprecationWarning: The popen2 module is deprecated. Use the subprocess module.
  import popen2
TESTING: checkArchiver from config.setCompilers(config/BuildSystem/config/setCompilers.py:930) *********************************************************************************
         UNABLE to CONFIGURE with GIVEN OPTIONS (see configure.log for details):
---------------------------------------------------------------------------------------
Could not find a suitable archiver. Use --with-ar to specify an archiver.
*********************************************************************************

Failure with exit status: 1
Exit message: There was a problem in build setup for petsc-3.0.0-p12.