There are a number of legitimate reasons why a student or child might not be receiving planned skills.
Your students will stop working on your plan under the following circumstances:
The end date for your plan elapses or the plan hasn't started yet
All plans have fixed start and end date as selected at the time of creation. Verify if your plan is active by logging into your account, selecting the appropriate class and selecting "planner" to view your calendar.
From this view you can select to edit your plan by left clicking on it and selecting "edit".
They master the selected skill(s)
Students will cease to receive planner skills once they've demonstrated mastery of that skill.
You can view if this is the case by left clicking on the plan in your calendar view and selecting "View Report". The student's name will be listed under the "Mastered" heading.
They fail out of the selected skill(s) due to answering several questions incorrectly
A student will not continue to receive planner skills if they are struggling with them. If they do fail out of a skill they'll temporarily be moved back to the normal line of questions.
They'll return to the planned skill once they've both answered 20 questions and commenced a new session (e.g. logged out and back in).
They're two grade levels away from the content
If students are currently placed two grade levels away from the content you're assigning through the planner then they will not receive the planner skills. For example, if your student is placed or overriden to Grade 1 and your planner skills are from grade 3, then we don't feel it's fair to provide them with material they're not prepared for. The same circumstance would apply for a student in placed in/overriden to Grade 5, where the material is likely to be less helpful for them.
You can always adjust this level using the grade override feature. Instructions can be found here.
If you've investigated these scenarios and none apply then it is likely the student is not using the account you've provided which is part of your class.
If the student is using a different account which is not paired to your class then they will not be able to receive your planner skills.
Seek to verify that they're logging in to the correct account in order to receive planned skills. If they are using an account other than the one provided, you can add it to both your class and the plan.
To add them to your class take the steps outlined in the article here.
Once they're a part of your class they'll automatically receive your planner skills.