The two sides of the same coin: Part 2

For the first post, please scroll down to the previous post.
Here is the second part of the story, from the supervisors point of view:

You're a senior researcher in a lab and for once, the professor handed you an important research project. Since it is the first time you got such a big project, you felt the stress from it. Several days into the project you find that the experiments were not going really well since the experiments requires new techniques that you have not fully master.

One day your professor assigns to you a student researcher who is in his third year of his undergraduate studies. You think that since he is in his third year, he should have gained enough lab experience to do proper lab work. (This presumption is however wrong, class lab experience that he has is insufficient to do proper work without supervision in a working lab. In class labs, students are guided closely step by step by instructions and TAs which is different from a working lab.

With that presumption in mind you handed him the project he is suppose to run on and proceed on with your own research. Once in awhile you would check in onto his progress and you found that he appears clumsy in his work. Due to your presumption on his lab skills, you think that he is fooling around in the lab and therefore gave him stern instructions in order to tell him to be serious about his lab work. For some reason, you also find that he seems to be very quite and timid when you are around however other lab mates says otherwise.
Besides that you find that he never asked for a proper meeting for his research project before so let it passed as "he knows what he is doing". He does occasionally ask you about the project, however you are normally in the midst of an experiment and therefore you could not give him your full attention.

One day you found out from a lab mate that he labeled you "dragon lady" and you are upset for receiving such unjust remarks from him. Being more mature, you decided to let this pass by and not bring the issue up. You do however begin to work more on your research and have less time to spend on the student.

As you continue to check on the student, you find that he is not progressing in his research as expected and therefore you decided that you should set a lab meeting with him and the professor the figure out the problem.

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This was the other part of the story. However let's consider this point, most of the time the senior staff would presume that the newer people will approach them by themselves if they have any issue and often has presumption on the newer staffs capabilities. Since senior staffs also have their own work to complete while newer staffs has less workload place on them, the seniors tend to concentrate more on their work and less on the newer staffs.

As a senior, how should we act in such situations? Especially when you have higher expectation on performance on you from your boss since you are more senior then the newer staffs.