A miss is as good as a mile
I'm not sure whether there are any genuine "laws of management" - principles that always apply. But one strong contender would be, "People are more likely to copy what you do than they are to do what you say." Another way of putting this is that organisational culture is most strongly influenced by the perceived values and beliefs of senior managers, as evidenced by their behaviours. This will always override any declared rules or standards.
I expect that most experienced managers are well aware of this phenomenon, but there's a corollary to it: people won't change until their leaders are perfect!
So, if you're trying to persuade your team to adopt a new system or practice, many of them will wait to see what you do. You might change some aspects of your behaviour in line with the initiative - so will the team follow your example? The enthusiasts certainly will. The rest will focus on what you're NOT doing and will use these lapses as their excuse for not changing themselves.
Even if you're 90% "on message", the missing 10% lets them off the hook. Only when you are perfect will they respond - and they don't expect that to happen any time soon!
This recalls the story of someone asking, "If NLP's so good, why aren't you practitioners all perfect?" And the answer was, "We're not perfect people, but we're getting better!"
Similarly, "If this new system is so good, why aren't you following it perfectly?" To which an answer might be, "I've moved on from where I was - and soon I'll be doing even better." And then you need people to follow your example.
Conversely, you could accept that you have to set a better example before you can expect anyone else to follow. Then you will have condemned yourself to trying to meet the standards that your "awkward" team members have turned round onto you - and which they will keep moving upwards as you approach the peak.
Better to tackle their inertia more directly.
The first thing is to make sure you're not playing their game yourself. Give others credit for what they have done - even if it's not all they could do.
Address the sceptics individually:
- They'll each have their own reasons for resisting change.
- They won't publicly acknowledge the benefits of your plans but might well in private.
- Make sure there's something in it for them - but check what they want first!
Admit your own shortcomings whilst re-stating (and demonstrating) your determination to improve.
Be very clear about the "non-negotiable" principles that underpin what you're doing - and then be very flexible about how the principles can be realised.
Support the people who are moving in the right direction. Some of them might influence their peers by bold, inspiring displays of leadership; laying out a vision that others want to share in and persuading them that it's achievable. Others get results just by nudging things in the right direction whenever they can; taking small actions and giving wise advice at the critical moment. By doing this consistently they make a difference. Usually, no-one else is aware of this so they go unrecognised, but you can look out for their positive contributions and make sure you let them know that you appreciate them.
Don't expect any thanks! You're introducing change because you know it's right and you'll gain great satisfaction from seeing the results. If, however, you're also desperate for personal recognition then you're going to be disappointed. (This is an example of a "value" that's very detrimental to you. Let me know if this is a problem for you and I'll be happy to help.)
Finally, it's important to be "hands-on", actively helping others to adjust to the change. This means investing time and effort in coaching your team members personally.
If all of this sounds sensible, but impossible, because you're "not the kind of person" who can lead people in this way, then I'd urge you to seek coaching yourself. Anything can be learned - and anyone can dramatically improve their leadership skills.