What methods should I use from the PythonCyc API to query metabolites in the BioCyc database?

I am using the PythonCyc API to write a request for metabolites in BioCyc . The purpose of this API is to communicate with the BioCyc-Pathway Tools software. Pathway Tools is in lisp, so PythonCyc creates a bridge between python and shared lisp. To use this API, you first need to create a PGDB object with the specified organism identifier (orgid). In the example below, I am creating a PGDB with the orgid "meta". After that, I can call methods from PythonCyc with this object:

import sys
import pythoncyc
#this creates PGDB object associated with meta(MetaCyc)
meta = pythoncyc.select_organism('meta')
#lists pathways of specified compound
pathways = meta.pathways_of_compound('sucrose')
print pathways

      

        
        
        
      

    

The metabolite query above, "sucrose", contains a list of pathways:

[u'|PWY-7347|', u'|SUCSYN-PWY|', u'|PWY-7238|', u'|PWY-6527|', u'|PWY-5343|', u'|PWY-3801|', u'|PWY-7345|', u'|PWY-862|', u'|SUCUTIL-PWY|', u'|PWY66-373|', u'|PWY-621|', u'|PWY-822|', u'|SUCROSEUTIL2-PWY|', u'|PWY-6525|', u'|PWY-6524|', u'|PWY-5337|', u'|PWY-5384|']

      

        
        
        
      

    

However, if I switch this metabolite name to a common amino acid name such as "valine":

import sys
import pythoncyc
#this creates PGDB object associated with meta(MetaCyc)
meta = pythoncyc.select_organism('meta')
#lists pathways of specified compound
pathways = meta.pathways_of_compound('valine')
print pathways

      

        
        
        
      

    

The request contains an error message that states "bearer frame", which means it cannot find this identifier. It is a common metabolite, like sucrose, which should very well have path records in the database, however, has not been found with this method. I have also tried synonyms for valine and other methods in PythonCyc like "all_pathways (cpds)" which gives me the same error message. What is causing this? BioCyc doesn't list any pathways for amino acids? Am I using the wrong method to access amino acid information?

PythonCyc API Reference