using custom Id column mapping with Searchable plugin

Question

I have a Domain class with a custom Id mapping

...
...
String ensemblGeneId
    String ensemblTranscriptId
    String ensemblProteinId
    String proteinSequence
    String topologySequence
    String topologyRatio
    String description
    String geneName

    ..       
    ..                                     
    ..

    static mapping = {
        proteinSequence type:'text'
        topologySequence type:'text'    
        description type:'text' 
        id name:'ensemblProteinId', generator:'assigned'    
    }

i have a problem making this work with the searchable plugin

i add the following to the class

    static searchable = {
    id name:'ensemblProteinId'
    except = ['topologySequence','proteinSequence']

}

I receive the following error after the data insert is completed

2010-07-06 13:35:08,091 [http-8080-1] ERROR errors.GrailsExceptionResolver  - Id with path [$/Protein/id] for alias [Protein] not found
org.compass.core.engine.SearchEngineException: Id with path [$/Protein/id] for alias [Protein] not found

it seems like it still tries to find a column named id instead of a column named ensemblProteinId.

is the searchable plugin supposed to work with custom id columns, if so what am i doing wrong?