need help with editing desc_mercenaries.txt

I am working on a small mercenary modification for CoW.
Today I encountered a problem with adding Nigth Goblins and Orc units as recruitable mercenaries for the Orcs.
Edit: The same problem with Dark- and High Elf units.

What I did:

1. opend the descr_mercenaries.txt and added the following entries:

pool Dwarves and Nightgoblins
regions Karaz_a_Karak_Province Zhufbar_Province Karak_Kadrin_Province Karak_Hirn_Province Karak_Ziflin_Province Kraka_Drak_Province Kraka_Ornsmotek_Province Karak_Gunbad_Province Karak_Varn_Province Karak_Vlag_Province Karak_Ungor_Province Mount_Silverspear_Province Karag_Dum_Province Karak_Eight_Peaks_Province
unit Quarrellers exp 2 cost 800 replenish 0.05 - 0.15 max 3 initial 3 religions { dwarven }
unit Dwarfs hammers exp 2 cost 800 replenish 0.05 - 0.15 max 3 initial 3 religions { dwarven }
unit Slayers exp 2 cost 1200 replenish 0.05 - 0.15 max 3 initial 3 religions { dwarven }
unit Chaos dwarfs warriors exp 2 cost 800 replenish 0.05 - 0.15 max 3 initial 3 religions { chaos }
unit Chaos dwarfs exp 2 cost 650 replenish 0.05 - 0.15 max 3 initial 3 religions { chaos }

So far no problems, BUT if I add any Orc or Nightgoblin unit to the rooster, like:

unit Orcz boyz exp 1 cost 800 replenish 0.05 - 0.15 max 3 initial 3 religions { islam }
unit Night Goblinz exp 0 cost 800 replenish 0.05 - 0.15 max 6 initial 6 religions { islam }

The game returns to the mainmenu after selecting a faction.

If I delete the Orcs and Night Goblinz units from the descr_mercenaries.txt, the game works fine again.

Any suggestions?

Edit: I tried to add the units without the "religions { islam }" restriction ==> failure
added the units with "factions { turks moors }" ==> failure