Validation warning! - Sampler value tex has not been set in fragment shader

[ste3e]

I have been figuring out how to use sampler2D uniforms but get the above error even though the shader validates and the program does what is is supposed... blend a given color with the texel color. The relevant code follows:

vertex shader:

varying vec4 vertColor;

void main(){
    gl_Position = gl_ModelViewProjectionMatrix*gl_Vertex;
    vertColor = vec4(0.6, 0.3, 0.4, 1.0);
    gl_TexCoord[0]=gl_MultiTexCoord0;
}

fragment shader

uniform sampler2D tex;
varying vec4 vertColor;


void main(){
    gl_FragColor = vertColor*texture2D(tex, gl_TexCoord[0].st);
}

lwjgl code in the render method:

if(useShader){
            ARBShaderObjects.glUseProgramObjectARB(shader);
        }
        int location=ARBShaderObjects.glGetUniformLocationARB(shader, "tex");
        if(location>0){
            ARBShaderObjects.glUniform1iARB(location, 0);
            GL13.glActiveTexture(GL13.GL_TEXTURE0);
            GL11.glBindTexture(GL11.GL_TEXTURE_2D, tex);
        }else{
            ARBShaderObjects.glUseProgramObjectARB(0);
            GL11.glBindTexture(GL11.GL_TEXTURE_2D, tex);
        }

        GL11.glBegin(GL11.GL_QUADS); // Draw A Quad

Having spend days trawling through what examples there are on the net I think I have the code right but still receive the warning. I am on a Radeon 5600 series.

[madeinsoviets]

Do you found problem?