If you move from one province to another with unused provincial tuition carried forward, you are usually limited to only using your federal unused tuition amount as your provincial amount (with some exceptions). The warning is there to remind you of this.
If you are sure that you have put in the correct amount, then you can ignore the warning. If you would like to review what you have put for your unused provincial tuition carried forward amount, select “Tuition Fees Carry Forward” under “Students” in the “Deductions” tab. If you make any changes on the “Your unused tuition and education amount” page, click on the “Continue” button or “Save” (top right) to save your changes.