In app purchase/ Apple ID funds

I took my used my debit card to purchase a $0.99 in app purchase earlier today and I bought a $30 iTunes gift card so I added that to my account and took my debit card off my account so I could purchase a $29.99 in app purchase and it wouldn’t use money from my debit card. So now when I try to purchase the $29.99 in app purchase it says insufficient funds.