Coupon Code misleading when pay

I have a product that has terms:

Free for the first 30 days, Then £29.00 GBP for each year

I have a coupon code that offers £1 for the first year.

When the client enters the code and goes to PayPal, there is no mention of the discount. The paypal screen say:

Description: Standard package
Terms: Free for the first 30 days, Then £29.00 GBP for each year
Amount: £0.00 GBP

There is no indication that the charge will actually be £1 after the 30 days.

Am I doing anything wrong or can coupons be not used when you offer a FREE period?

Thanks,
Ian

Thanks for the quick response.

I think I will just adjust the payment plan to be £1 for the first year and £29 for all others and remove the 30 day free trial. I can then set this back after the promotion has finished.

Thanks,
Ian