HeliControl.cs(1026,17): warning CS0219: The variable `callTarget' is assigned but its value is never used
HeliControl.cs(1027,17): warning CS0219: The variable `callSelf' is assigned but its value is never used
HeliControl.cs(1190,17): warning CS0219: The variable `newHelis' is assigned but its value is never used
HeliControl.cs(1464,17): warning CS0219: The variable `newHelis' is assigned but its value is never used

can someone explain me what is this? 
i also get same warning with other plugins i used on my server. 

Those are warnings, not errors. They will not affect the plugin usage.

i see, thanks wulf