Just use this procedure :
SCAR Code:
{*******************************************************************************
procedure Mouse(mousex, mousey, ranx, rany: Integer; left: Boolean);
By: Mutant Squirrle, with a small fix by hy71194
Description: Moves then clicks mouse.
*******************************************************************************}
You will need to include SRL though
:
It clicks exactly like you want it to, it moves humanly, and clicks while holding a small amount of time...
If this wasn't your answer tell me
.
For example, this will click humanly at the Main Screen down right corner 
SCAR Code:
Mouse(MSX2,MSY2,0,0,true);
MSX2 : is the X position of the down right corner
MSY2 : is the Y position of the down right corner
0 : the randomness to add to the click (in pixels) on X axis
0 : same as the first 0 but for the Y axis
true : left click, false : right click
I hope you understand...