Mines doesn't explode

Hello,
I've been playing mines for the first time and now i have a problem.
i've started with pyroclast mine, and i want to change to hexblast using high-impact mine supp. After i have placed gems in eq and wanted to use hexblast they don't explode except skitterbots discharging them. On Detonate skill, i see i'm using it, but nothing happens except a small flash on weapon. Changing again to pyroclast i can detonate them again.

Ok, i believe i found a problem, they don't explode unless there is a target near... But why? if other work normally, others should also. Ofc unless that's hexblast specification