What is it with Tactics ?
They don't deduct points when you get it right. They used to do that. A lot of people complained. Now you can take as long as you want. You may not earn many points for a slow right answer but you will at least not lose any.
You have to keep at it. You are not doing badly.
I can work with you on calculations and tactics. Check out www.premierchess.com or email erabin66@gmail.com to learn more about my chess career and instruction services.