Can't lock onto Data Link shared targets

[Kreu 16]

Following situation:
I placed a radar in the editor. radar is active and it shares all data link info.
i fly in a black wasp with the abillity to receive data link, but radar is turned of at all time. an enemy jet is approaching the position of the radar. 

 

I expected to be able to lock onto the ememy incoming jet with my medium range radar guided missiles. 

 

But i can't. I can see the enemy jet on the sensors panel, because my allied radar detected him and sends me his position. but i cant lock onto him until im closer than 1km.

 

If i use the defender SAM site i can lock onto enemys via Data Link. 

 

My Question:
Am i doing something wrong or is the black wasp just not able to lock onto data link shared targets?
Also why can i suddenly lock onto them when the distance is less than one km?

[Kreu 16]

Got an answer on reddit.

In case anybody ever has the same question, here is the answer

 

The AMRAAM D missile carried by the F/A-181 has a Semi-Active Radar Homing guidance package. This requires the launching aircraft to illuminate the target with its onboard Active Radar (Fire Control) system to lock, launch and guide to impact.

The data link allows the Black Wasp to close to within lethal attack range before lighting up (turning on the Active Radar system) thus minimizing adversary reaction time. If you wish to attack full stealth you'll have to use the BIM-9X IR guided missile or the gun (and get much closer).

When target distance is under 1 km, apparently you are able to get a visual detection but you still shouldn't be able to shoot the AMRAAM w/o your active radar. Note minimum range is 800 m for the AMRAAM.

The MIM-145 Defender missile system uses a different type of guidance that requires a (remote) active radar system to guide it. In other words, its only function is to get the missile in the air. This allows a single radar to control multiple missile batteries just like IRL.

 

Answer is from KillAllTheThings from Reddit

[stanhope 409]

You can also fire it without a lock and the amraam will lock onto the first target it sees.  This can be dangerous when there's friendly aircraft around as you have no control over what it locks and doesn't guarantee success as it might fail to acquire a lock.