Training skills are a completely different bag of tools to teaching skills.
We once had an 'A' level ICT teacher who came to work for us as a teacher trainer. Although she got on well with everyone (teachers and pupils alike), her IT skills were fantastic and she had brilliant results as a teacher, it took her a while to settle into being a teacher-trainer - to get over the fact that she was teaching her peers.
At times she was almost apologetic for having to tell the teachers something. She also tended to assume that the teachers she was teaching already knew the fundamentals (which is the image some teachers are so practised in projecting!)

We asked our new trainer to shadow an experienced IT trainer for a while - someone who had trained everyone from captains of industry to boy scouts - and make notes on any differences in their styles of training.

• The main difference was the way in which the experienced trainer introduced the session. Teachers were told that the experienced trainer would assume no prior knowledge. This meant that it was OK not to know something, but that the teachers wouldn't have to admit to not knowing it (a vital point)!
  On the flip side, our experienced trainer also "bigged up" the fact that if you DID already know something then that was brilliant and they could sit back and look good. Explaining that in the Windows environment there are often three or four different ways of doing something and that they would be learning the best practice route. As well as saving time the teachers would understand the process behind the action... and therefore understand what to do if it didn't work. This built the teachers' confidence as well as competence.
  
  
• Another important trick to teaching teachers our less experienced trainer came away with... don't give the teachers the text books until the END of the training session!
  As our ECDL for Educators courseware is written click-by-click it can be tempting to stop listening to the trainer and run ahead on your own. The experienced trainer only photocopied the end example i.e. the result of the exercise (like in Blue Peter, here's-one-I-made-earlier). In this way the teachers could see what it was they were trying to create - but not how to get there!
  There was no "modelling" and no demoing on a whiteboard, the teachers HAD to listen to the trainer's instructions and then carried out the instruction on their own computer. This learn-by-doing method puts the teacher in control of the technology, but at a speed dictated by the trainer.
  
  
• The final training tool used by our experienced trainer to keep all of the teacher-learners together was to turn anything going wrong or not working on a teacher's computer into a positive experience. The trainer would stop the whole session, draw everyone's attention to the misbehaving hardware/software and encourage them to work out together WHY it had gone wrong and what they could do to put it right. Troubleshooting in this way not only built confidence in the technology but also made sure that any click-happy-Harry's weren't tempted to leave the others behind.