[Konstantinos]

To start off, you need to show the code as well because only the errors are obviously not very useful.

You also need to get an idea of how threaded queries work: https://sampforum.blast.hk/showthread.php?tid=337810
Sure the tutorial is kind of old (for R7) but you can pretty much understand what's the concept.
Take a look at wiki for the new functions and how are used: https://sampwiki.blast.hk/wiki/MySQL/R33