It's a fact of mediation that not every mediated conflict ends perfectly, tied up in a Lovely Pink Bow. I don't want you to feel bad if you kids weren't able to reach a solution. And I want to remind you, by way of encouragment, what did happen despite the lack of an “LPB.” They agreed to ground rules. This is huge - it signifies a degree of trust in you and in the process. They shared their wants, needs and feelings with each other. And they listened. All of those things buttress a relationship even when an actual agreement is out of reach. Truly, it wasn't a waste of your time or theirs.
Now watch and wait…and trust percolation. Sometimes just the unpacking and venting does the trick. You may notice a subtle shift in their dyamic. There might be some self-reflecting going on that was sparked by things that were said and heard in the mediation. People often change withut an explicit promise to do so. Time will tell.
And what about you? Did you reflect on the process? You might come up with questions that went unasked in the mediation, or better ways to ask those questions that you did ask. Your kids wobbled when they were learning to walk; give yourself permission to wobble a little as you learn this technique.
And whatever you do, keep mediating!