Most likely your balance is too small. The staking difficulty is actually pretty high. I have not finished syncing my wallet, so I have not actually tried to stake yet.

Keep in mind that 1,000,000 sprouts is about 12 dogecoin at the current price on coinexchange.io.

Did you downnoad the latest wallet? There was a reward reduction to stop this coin from imploding by hyperinflation. Download it at the main website, https://www.sprouts-coin.org/en/ or compile it from the github repository https://github.com/SproutsCommunityRep/sprouts