Context node not found when using label Follow

OK, so I'm finally starting on the generation phase of my test language. Let's say I have the following:

record  RGB               

   Red : UnsignedInteger8 

   Green : UnsignedInteger8

   Blue : UnsignedInteger8

end record                

Lines like "Red : UnsignedInteger8" are FieldDeclarations. There are a number of primitive types that a field can be defined as, so I'm using weaving rules to generate read/write method calls to my binary stream runtime lib. However, I'm getting an error that the context node for the weaving rule cannot be found. I've defined a mapping label:

label statement : <no input concept> -> ClassConcept

and I've attached that to a root mapping rule:

concept Record          --> statement : map_Statement

inheritors false                                    

condition <always>                                  

keep input root default                             

then in my weaving rule, I select the FieldDeclaration by the type and forward that to a template using "statement" as the context:

concept FieldDeclaration                                       -->weave_UI8                                              

inheritors false                                                  context: (node, genContext, operationContext)->node< > {

condition (node, genContext, operationContext)->boolean {                     genContext . get output statement ;         

             node . type . isInstanceOf ( UnsignedInteger8 ) ;             }                                              

          }                                                                                                               

but apparently "statement" cannot be found. FWIW, map_Statement is a ClassConcept and I want to use a template fragment to define the body of two methods in that Class. Any suggestions as to why that label is not working?

Thanks,

Kevin