You probably have to add the complete material section + the reference for it in the HUD section :
....
[HUD] HUDMaterial=HUDMaterial .... [HUDMaterial] EffectShaderName=fltHUD.fx DepthBufferCheck=FALSE DepthBufferWrite=FALSE RenderedInOrder=FALSE AlphaTestEnabled=TRUE CullMode=NO_CULL LightEnabled=FALSE UseLightLevel=FALSE SpecularEnabled=FALSE EmissiveEnabled=FALSE FogEnabled=FALSE AmbientColor=1.000000,1.000000,1.000000,1.000000 DiffuseColor=1.000000,1.000000,1.000000,1.000000 ZBufferOffset=0 PriorityLevel=1 BlendOp=BLEND_SRC_ALPHA NumTextureStages=1 TextureStage[01].TextureName= TextureStage[01].MipMap=FALSE TextureStage[01].FilterEnabled=TRUE TextureStage[01].StageColorOp=TEXTURE_MODULATE_DIFFUSE TextureStage[01].StageAlphaOp=TEXTURE_MODULATE_DIFFUSE