stupid 
  
add  in you WEAPONDATA.INI 
  
[WeaponData0xx] 
TypeName=lewis01 
FullName=Lewis mount 
ModelName=lewis1.LOD 
Mass=20.000000 
Diameter=0.100000 
Length=1.200000 
AttachmentType=NATO,FRANCE 
NationName=FRANCE 
StartYear=1915 
EndYear=1918 
Availability=2 
BaseQuantity=100 
Exported=TRUE 
ExportStartYear=1915 
ExportEndYear=1918 
ExportAvailability=2 
WeaponDataType=3 
GunTypeName=303CAL_LEWIS_MK2 
MaxRounds=94 
MuzzlePosition=0.000000,0.700000,0.250000 
LightPosition=0.000000,0.700000,0.250000 
AimDirection=0.000000,0.000000,0.000000 
EjectShells=0 
  
and use weapon editor for WOI on your WEAPONDATA.INI 
  
normaly it work  
  
sorry