[MarkNelson]

you just did a mistake you forget to type "Player"
it's like this
"FCNPC_OnPlayerTakeDamage"

PHP Code:

error 025: function heading differs from prototype
error 017: undefined symbol "damagerid"
error 025: function heading differs from prototype 


Line 279 :

PHP Code:

public OnPlayerTakeDamage(npcid,playerid, issuerid, Float:amount, weaponid, bodypart) //This is the line 279
{
    #if defined FCNPC_OnPlayerTakeDamage
        return FCNPC_OnPlayerTakeDamage(npcid, damagerid, weaponid, bodypart, Float:health_loss); //This is 282
    #else
        return 1;
    #endif
} 


and here is LINE 295 :

PHP Code:

    forward FCNPC_OnPlayerTakeDamage(npcid, damagerid, weaponid, bodypart, Float:health_loss);