Thank you for your post.
This normally happens when there isn't a material selected as there are sections of the Wall Tool that use materials to set the sizes/thicknesses of the wall skins. There are two thing I would recommend to do, which are:
1) Go to the 'Materials, Selections & Finishes' section of the Wall Tool dialog and make sure there's a material selected for the outer skin of the wall (where the brick would be), then try to draw a wall again.
2) Go to the Settings Tool (go to 'Extensions > PlusSpec > Settings') and make sure that the correct options are selected there, then use the Sync Tool (if any changes are made to the Settings Tool it should sync automatically when you press 'Submit'). Please note that after doing this you may need to try 'Option 1' again. After doing this, try and draw a wall again.
Would you be able to please let me know if this fixes the issue you're having?