Say what!?

One object goes:

llSay(-20090929,"Whatever");

But the other object doesn't appear to be paying attention:

list particle_parameters;
float SystemSafeSet;
float SystemAge;

StartParticles()
{
    llParticleSystem([
           PSYS_PART_START_SCALE, <0.015,0.015,FALSE>,
           PSYS_PART_END_SCALE, <1,1,FALSE>, 
           PSYS_PART_START_COLOR, <0.3,0.3,0.3>,
           PSYS_PART_END_COLOR, <0.8,0.8,0.8>, 
           PSYS_PART_START_ALPHA, (float) 0.05,
           PSYS_PART_END_ALPHA, (float) 0,   
           PSYS_PART_MAX_AGE, (float) 1,
           PSYS_SRC_MAX_AGE, SystemSafeSet, 
           PSYS_SRC_BURST_PART_COUNT, (integer) 20, 
           PSYS_SRC_BURST_RATE, (float) 0.01,  
           PSYS_SRC_PATTERN, (integer) 4,  
           PSYS_SRC_BURST_SPEED_MIN, (float) 0.25,
           PSYS_SRC_BURST_SPEED_MAX, (float) 1.5, 
           PSYS_SRC_ANGLE_BEGIN, (float) 0.9 * PI,
           PSYS_SRC_ANGLE_END, (float) 1.1 * PI,  
           PSYS_SRC_OMEGA, <0,0,0>,
           PSYS_SRC_ACCEL, <1.5,0,1.5>,  
              
           PSYS_PART_FLAGS, (integer)( 0     
                                | PSYS_PART_INTERP_COLOR_MASK   
                                | PSYS_PART_INTERP_SCALE_MASK
                                | PSYS_PART_EMISSIVE_MASK   
                                | PSYS_PART_FOLLOW_VELOCITY_MASK
                            ) 
        ]);
        llSleep(SystemAge);
        SystemSafeSet = 0.00;
        }

default
{
    state_entry()
    {
        SystemSafeSet = 0.00;
        SystemAge = 1.5;
        llListen(-20090929, "", NULL_KEY, "");
        }
        listen( integer channel, string name, key id, string message )
        {
            if (message == "Whatever") StartParticles();
            }
            }     

Any ideas what's wrong here?

Replacing the Startparticles() call with an llSay shows that it hears the other object fine, so that's a red herring. The problem is in the particle generator.

Ah.. the particles are there but are almost invisible!

PSYS_PART_START_ALPHA, (float) 0.05,
PSYS_PART_END_ALPHA, (float) 0,

If you change both to 1 you will see them!

Thanks Ee, but I have an almost exactly similar particle system operating in another Hud-controlled object I made sometime back. The effect is subtle - something like breath on a frosty morning - but it is certainly visible thanks to the emmissive mask:

list particle_parameters;
float SystemSafeSet;
float SystemAge;

StartParticles()

{
    SystemSafeSet = SystemAge;
    
    llParticleSystem([
    
        PSYS_PART_START_SCALE, <0.15,0.15,FALSE>,    
        PSYS_PART_END_SCALE, <0.5,0.5,FALSE>,
        PSYS_PART_START_COLOR, <0.35,0.35,0.25>,    
        PSYS_PART_END_COLOR, <0.75,0.75,0.75>,
        PSYS_PART_START_ALPHA, (float) 0.04,        
        PSYS_PART_END_ALPHA, (float)0.0,
        
        PSYS_SRC_BURST_PART_COUNT, (integer) 15,
        PSYS_SRC_BURST_RATE, (float) 0.1,
        PSYS_PART_MAX_AGE, (float) 1,
        PSYS_SRC_MAX_AGE, SystemSafeSet,
        PSYS_SRC_PATTERN, (integer)10,
        
        PSYS_SRC_BURST_SPEED_MIN, (float)0.1,
        PSYS_SRC_BURST_SPEED_MAX, (float)0.25,
        PSYS_SRC_ANGLE_BEGIN,  (float)0.05*PI,
        PSYS_SRC_ANGLE_END, (float)0.0*PI,
        PSYS_SRC_ACCEL, <0.25,0.0,0.125>,
        
        PSYS_PART_FLAGS, (integer)( 0
            | PSYS_PART_INTERP_COLOR_MASK
            | PSYS_PART_INTERP_SCALE_MASK
            | PSYS_PART_EMISSIVE_MASK
            | PSYS_PART_FOLLOW_VELOCITY_MASK
            | PSYS_PART_BOUNCE_MASK
            )
            ]);
            
            llSleep(SystemAge);
            SystemSafeSet = 0.00;
            }
            
default
{
    changed(integer change)
    {
        if(change & CHANGED_OWNER)
        {
            llResetScript();
            }
            }
            state_entry()
            {
                SystemSafeSet = 0.00;
                SystemAge = 1.5;
                llListen(-291009, "", NULL_KEY, "");
                }
                listen(integer channel, string name, key id, string message)
                {
                    if (llGetOwnerKey(id) != llGetOwner()) return;
                    else if (message == "Breathe") StartParticles();
                    }
                    }

The only significant difference between the two systems is that this 'breath' version resets at the beginning and ties the listen to the owner, which I don't want in this instance.

Just for the record, in case other scriptily challenged individuals pull this thread up for reference in the archived future: I neglected to declare 'SystemSafeSet = SystemAge;' in the problematic script. Of course it's there in the working example but why the hell would I want to look at that when I could spend all day bouncing my head off the desk?