Mary, is the location where you started burying in dirt a familiar training location or was it a new environment for Lola to be playing this game?
Now I understand what you want to do and why…let me know about the above questions. Putting dirt in the container may not be necessary though. If it is actually the environment that is difficult for her, I’d suggest taking the “box game” to the new environment and progressing that way. Let me know and we can problem solve from there.