I'm trying to write a vertex shader to perform directional lighting. The ambient component of my lighting works but I don't get any lighting at all from the diffuse or specular components.

This is my vertex shader:
[source]
#version 130

struct Material {
vec4 emission, ambient, diffuse, specular;
float shininess;
};


struct DirectionalLight {
vec4 position, ambient, diffuse, specular;
};


uniform mat4 modelViewProjectionMatrix, modelViewMatrix;

uniform vec4 globalAmbient;

uniform Material material;

uniform int numDirectionalLights;
uniform DirectionalLight directionalLights[8];


in vec4 in_vertexA, in_normalA, in_texCoord;


out vec4 frag_texCoord, frag_frontColor;


void main() {
vec4 frontColor = globalAmbient * material.ambient;

vec3 eyeNormal = normalize(vec3(modelViewMatrix * in_normalA));
vec3 eyeVertex = vec3(modelViewMatrix * in_vertexA);

for (int i = 0; i < numDirectionalLights; ++i) {
vec3 lightDirection = normalize(vec3(modelViewMatrix * directionalLights.position));
float normalDotLightDirection = max(dot(eyeNormal, lightDirection), 0.0);

frontColor += material.ambient * directionalLights.ambient;
frontColor += normalDotLightDirection * material.diffuse * directionalLights.diffuse;

if (normalDotLightDirection > 0.0) {
vec3 reflection = -2.0 * eyeNormal * normalDotLightDirection + lightDirection;
frontColor += material.specular * directionalLights.specular * pow(dot(reflection, eyeVertex), material.shininess);
}
}

frag_texCoord = in_texCoord;
frag_frontColor = frontColor;
gl_Position = modelViewProjectionMatrix * in_vertexA;
}
[/source]

I'm not using a normal matrix now but I don't think that matters if I'm not scaling. Does anyone see any obvious problems with this shader? I've checked my normals and they all seem to be right.