blockchain.info – Blockchain app says payment amount exceeds limit.

I have a blockchain app on my iPhone that I’ve been using regularly for years, but haven’t actually used it in the last four months. I currently have about $2000 worth of BTC in my personal wallet. I just went to buy something that costs about $50. I clicked Send, selected my private key wallet, and entered the recipient’s address, but when I entered $50, it said in red that I was trying to send over the limit. Can anyone tell me what’s going on?