Show Validation on Icon click using submit link

I have requirement to deactivate task with following requirements:

1. A list of Task is displayed and each task has Deactivate icon next to it
2. Clicking on Deactivate icon, check if task is used as precedent for other task

3. If that task is used as precedent task then deactivate action should not proceed and Validation msg should appear on UI

4. If task is not used as precedent task,  then task should be deactivated and update action is executed where record column isDeleted as marked as true

5. Currently for this Deactivate icon Submit link is used, which proceeds deactivation action on click

 I am facing issue for showing up Validation msg in UI

- with Submit Link/Button: 

it executes the Deactivation action for non Precedent Task 

but fails to show validation msg on UI(in Design interface validation msg is showing up)

-with Dynamic Link:

successfully shows the validation msg on UI if task is used as precedent task, but fails to deactivate task which is not used as precedent task