Checking your wallet, I stumbled upon this:

You have been blacklisted due to violation of our terms of service! If you believe this was done in error, please contact us on discord: https://discord.gg/9HX2MVA. We'll stop refunding in 5 attempts.

Errors happen so I recommend contacting them, but first I want you to think of this.

Have you misused @minnowbooster in any way?

While they aren't picky about which to vote, they have some quality standards you can check their full rules here. But I'll take This post by you for example for posts not boostable with MB:

• Post is less than 150 words.

Using a MB vote for very short or repetitive content. Length is subjective, but 150 words is a good safe guideline.

• Few pictures, without mentioning the source (if you took them say so, but if you took it from any other place online they WILL know.)

Photography posts must contain supporting text and show significant effort in terms of production value (location, setup, lighting and subject) to be considered boostable.

Sorry if I took one of your 'bad' posts, I hope your other posts are better... I liked the flower pictures but at the same time I feel you could write more about where you took them, when & other 'personal things.

I love reading things you can't find in google, like your own experiences. I know you can do it. Lets make STEEM better!!

Finally

If you tried to upvote more than 3 posts at the same day, or made 3 failed attempts to boost a post... The system might think you're abuser. If that was the case, talking with the team on Discord might help.