Example:
You spawn a AW159 (Lynx) helicopter and fire it rockets.

You'll get kicked for create vehicle restriction #17

Check your logs for your createvehicle.log (another kick another log to check of course)

You'll find this:
19.06.2014 11:43:22: Stollenwerk (IP DELETED:2334) UID DELETED - #17 "M_CRV7_AT" 3:35 3:31 [16132,7993,516] [0,-8,9]

You see the #17 and the M_CRV7_AT is what we finally got kicked for. (the rocket)

Now go to your BEC folder and check out the createvehicle.txt

//new
1 "" !="WeaponHolder" !="TinCan" !="Rabbit" !="Goat01_EP1" !="Goat02_EP1" !="Goat" !="WildBoar" !="Sheep" !="Sheep02_EP1" !="Sheep01_EP1" !="Hen" !="Cock" !="Cow01" !="Cow02" !="Cow03" !="Cow04" !="Cow01_EP1" !="zZombie_Base" !="z_hunter" !="z_teacher" !="z_doctor" !="z_suit1" !="z_suit2" !="z_worker1" !="z_worker2" !="z_worker3" !="z_villager1" !="z_villager2" !="z_villager3" !="z_soldier" !="z_soldier_heavy" !="z_soldier_pilot" !="z_policeman" !="z_priest" !="BoltSteelF" !="Land_Fire_DZ" !="SodaCan" !="JackDaniels" !="RoadFlare" !="ChemRed" !="ChemBlue" !="ChemGreen" !="Survivor1_DZ" !="Survivor2_DZ" !="Survivor3_DZ" !="SurvivorW2_DZ" !="Bandit1_DZ" !="CZ_VestPouch_EP1" !="DZ_Patrol_Pack_EP1" !="DZ_CivilBackpack_EP1" !="DZ_ALICE_Pack_EP1" !="SmokeShell" !="SmokeShellRed" !="SmokeShellGreen" !="MedBox0" !="Camo1_DZ" !="Soldier1_DZ" !="DZ_Backpack_EP1" !="Sniper1_DZ" !="DZ_Assault_Pack_EP1" !="BanditW1_DZ" !="G_40mm_HE" !="dog" !="WeaponHolder_MeleeCrowbar" !="WeaponHolder_ItemHatchet" !="WeaponHolder_PartGeneric" !="WeaponHolder_ItemJerrycan" !="WeaponHolder_PartFueltank" !="WeaponHolder_PartGlass" !="WeaponHolder_PartEngine" !="WeaponHolder_PartWheel" !="WeaponHolder_PartVRotor" !="DZ_Czech_Vest_Puch" !="DZ_British_ACU" !="DZ_TK_Assault_Pack_EP1"
1 "SeaGull"
5 "box" !="DebugBoxPlayer_DZ" !="MedBox0" !="AmmoBoxSmall_556" !="AmmoBoxSmall_762" !="ItemMatchbox" !="ItemToolbox" !="CardBoardBox" !="FoodBox1" !="FoodBox2" !="FoodBox3" !="LockboxStorageLocked" !="LockboxStorage" !="WeaponHolder_ItemLockbox" !="USOrdnanceBox"
5 "Mine"
5 "ARTY_"
5 "SADARM_"
5 "LASER_"
5 "WP_"
5 "_MLRS"
5 "_81"
5 "_82"
5 "_105"
5 "_120"
5 "_122"
5 "_227"
1 "Bo_"
5 "_AA" !"Soldier_Bodyguard_AA12_PMC_DZ"
5 "_AT" !="R_M136_AT"
1 "R_M136_AT" //keep monitoring to catch obvious abuse

The first line is commented out (//New), so this line doesn't count.
Start with the second line, as line 0. That means that 19 is the line that prevents that weapon from being fired.

Means:
5 "_AT" !="R_M136_AT"

We were kicked for "M_CRV7_AT".
As you see at the beginning of that line is 5 "_AT".
That means that if someone fires a weapon that has _AT in it, he will be kicked (5 means kick. 1 means simply log it).
So, we need to add an exception for this weapon.

Change line 19 to this:
5 "_AT" !="R_M136_AT" !="M_CRV7_AT"

I hope this clarifies how to edit your filters.