You have added a new activity in the vPlan configuration, but it is not yet visible when you create a card in the plan board and want to add the activity to it. How is that possible?
In addition to creating an activity in the vPlan configuration, you must also link it to your board. More specifically, you need to link it to a stage in your board.
Follow this step-by-step plan to link the activity to a stage:
Go to Settings in the left menu bar of vPlan
Then click on Boards
Open the board to which you want to link the new activity by clicking on the name of the board
You will now end up in the settings of the board. Click on the Stages tab here. You now see at least one stage, but there may also be several (depending on your set up).
Open the stage's settings by clicking on its name
In your stage settings, go to the Activities tab
Search for your new activity in the Available column
Drag the activity with your mouse to the left Active column
Finally, click Save at the bottom of the page
Now you have linked the activity to this stage and you can choose the activity from cards that are planned on this stage.