Hey there. 
Please check if you have at least 1000 Veil in your basecoin balance for the automint. You can also manually mint your Veil by going to the Zerocoin Mint screen, typing in 1000, if using basecoin you can check "Use Basecoin" box, and hit MINT. If you are doing multiple mints for 1000 denominations you can input a max of 9000 at a time for minting.
Gray stakes means that you got an orphan stake, which is when you compete with someone else for the stake and lose. This can happen every now and then.
Thanks,I have my first valid stake.Zerocoin balance is 1120,if I set automint full balance then all zerocoins will take part in staking or 1000 only? Please check if you have at least 1000 Veil in your basecoin balance for the automint. You can also manually mint your Veil by going to the Zerocoin Mint screen, typing in 1000, if using basecoin you can check "Use Basecoin" box, and hit MINT. If you are doing multiple mints for 1000 denominations you can input a max of 9000 at a time for minting.Gray stakes means that you got an orphan stake, which is when you compete with someone else for the stake and lose. This can happen every now and then.