Like always?!
Really?

K, I think then I forgot something.

Maybe, I've to register the Entity (cube_0.mdl) on the Server?
Because, if I click on the Cube in the Client-Window, nothing happens.

Code:
////////////////////////////////////////////////////////////////////////
// Multiplayer Test Project
////////////////////////////////////////////////////////////////////////
#include <acknex.h> 
#include <default.c>
////////////////////////////////////////////////////////////////////////
FONT* font_arial = "Arial#20b";
////////////////////////////////////////////////////////////////////////
STRING* str_Message1 = "#30";
////////////////////////////////////////////////////////////////////////
BMAP* BMAP_MouseMap = "mouse_0.tga";
////////////////////////////////////////////////////////////////////////
VECTOR* vec_ServerMove = {x=0;y=0;z=0;}
////////////////////////////////////////////////////////////////////////
ENTITY* ent_Camera = 0;
////////////////////////////////////////////////////////////////////////
TEXT* t_DEBUG =
{ 
	pos_x = 10;
	pos_y = 10;
	font = font_arial;
	string = str_Message1;
	flags = VISIBLE;
}
////////////////////////////////////////////////////////////////////////
function fEVENT_Cube()
{
	switch(event_type)
	{
		case EVENT_CLICK:
		{
			printf("YES !!!!");
			break;
		}
	}
}
////////////////////////////////////////////////////////////////////////
function fROOT_Cube()
{
	my.event = fEVENT_Cube;
	my.emask |= (ENABLE_CLICK);
}
////////////////////////////////////////////////////////////////////////
function fROOT_Camera()
{
	if(ent_Camera != 0)
	{
		while(1)
		{
			camera.x = (ent_Camera.x - 400);
			camera.y = ent_Camera.y;
			camera.z = (ent_Camera.z + 100);
			wait(1);
		}
	}
}
////////////////////////////////////////////////////////////////////////
function fROOT_Player()
{
	while(1)
	{
		vec_ServerMove.y -= my.skill10;
		vec_ServerMove.x += my.skill11;
		vec_ServerMove.z += my.skill12;
		c_move(my,vec_ServerMove,nullvector,IGNORE_ME);
		vec_set(vec_ServerMove,nullvector);
		ent_sendnow(my);
		wait(1);
	}
}		
////////////////////////////////////////////////////////////////////////
function fROOT_CreatePlayer()
{
	switch(connection)
	{
		case 2:				// Client
		{
			my = ent_create("player_0.mdl",vector(0,0,150),fROOT_Player);
			wait(1);
			ent_Camera = my;
			while(1)
			{
				my.skill10 = key_force.x * time_step * 5;
				my.skill11 = key_force.y * time_step * 5;
				my.skill12 = 0;
				send_skill(my.skill10,SEND_VEC);
				fROOT_Camera();
				wait(1);
			}
			break;
		}
		default:			// Server-Client/Error
		{
			my = ent_create("player_0.mdl",vector(0,0,150),fROOT_Player);
			wait(1);
			ent_Camera = my;
			ent_create("cube_0.mdl",vector(100,100,50),fROOT_Cube);
			wait(1);
			while(1)
			{
				my.skill10 = key_force.x * time_step * 5;
				my.skill11 = key_force.y * time_step * 5;
				my.skill12 = 0;
				fROOT_Camera();
				wait(1);
			}
			break;
		}
	}
}
////////////////////////////////////////////////////////////////////////
function main() 
{
   fps_max = 60;
   fps_lock = ON;
   mouse_map = BMAP_MouseMap;
   mouse_mode += 2;
   mouse_range = 2000;
   level_load ("level_0.wmb");
   switch(connection)
   {
   	case 2:			// Client
   	{
	   	str_cpy((t_DEBUG.pstring)[0],"Client");
	   	break;
	   }
   	default:		// Server-Client/Error
   	{ 
	    	str_cpy((t_DEBUG.pstring)[0],"Server-Client/Error");
	    	break;
	   }
   }
   fROOT_CreatePlayer();
   while(1)
   {
   	vec_set(mouse_pos,mouse_cursor);
   	wait(1);
   }
}
////////////////////////////////////////////////////////////////////////
// E O F
////////////////////////////////////////////////////////////////////////


These tomorrow, I will read the Loocoweed Tutorials and I hope, after this becomes some clearly.