SweetlySouthern Melody

Here's the Problem: Yesterday, I was able to purchase 5000L but then when I went back in to purchase another 20000L it wouldn't let me. The card/paypal that i'm using as plenty of money so there's no reason why it shouldn't work. However when I click "Buy Now" it says "Payment Cancelled". Someone thought it may be because I've some how reached my Purchase Limit of Lindens, so how do I raise it? And is anyone else having the same trouble?