Oracle recursive request

[Gaelle]

Hi !

I have a request problem : I don't manage to write what I want...
I have two tables :
MODEL SUB_MODEL
_____ _________
MDL_CODE MDL_CODE_SON
MDL_LABEL MDL_CODE_FATHER

It is recursive on sub_model, where MDL_CODE_SON can be a MDL_CODE_FATHER and son on. I would like to be able, for a given model m in table MODEL, to get all the path
MODEL1/MODEL2/.../MODELN/m
I'm trying to use keywords like sys_connect_by_path(MDL_LABEL, '/'), but I never manage to get the full path.
For example, the very first model of the path misses, since it has no father model.

Can someone help me ?

Thanks so much.