当检索现有着色器属性时，glGetAttribLocation返回-1

我试图将属性传递给我的顶点着色器，但由于某种原因，它一直给我一个-1在第三个属性位置，我要求openGl通过glGetAttribLocation()检索。目前它一直给我一个-1的texCoord属性，如果我切换texAttrib和colAttrib周围(切换行代码)它给我一个-1的颜色属性，而不是纹理，我不知道为什么?由于-1被传递给glVertexAttribPointer，我得到1281 OpenGL错误:GL_INVALID_VALUE。

顶点着色器:

#version 150
in vec3 position;
in vec3 color;
in vec2 texcoord;
out vec3 Color;
out vec2 Texcoord;
void main()
{
    Color = color;
    Texcoord = texcoord;
    gl_Position = vec4(position.x, position.y, position.z, 1.0);
}

basicShader.Use();
// Buffers and shaders
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glGenBuffers(1, &vbo);
// Make it active vbo
glBindBuffer(GL_ARRAY_BUFFER, vbo);
// Build basic triangle
float vertices[] = {
    // position         // color          // textures
    -0.5f,  0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // Top-left
     0.5f,  0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Top-right
     0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, // Bottom-right
    -0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f// Bottom-left
};
GLuint elements[] = {
    0, 1, 2,
    2, 3, 0
};
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
GLint posAttrib = glGetAttribLocation(basicShader.shaderProgram, "position");
glEnableVertexAttribArray(posAttrib); // Enable attribute first before specifiying attributes
glVertexAttribPointer(posAttrib, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), 0); // 6 float sizes is every new vertex
GLint colAttrib = glGetAttribLocation(basicShader.shaderProgram, "color");
glEnableVertexAttribArray(colAttrib);
glVertexAttribPointer(colAttrib, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); // same for color + offset
GLint texAttrib = glGetAttribLocation(basicShader.shaderProgram, "texcoord"); // Returns -1
glEnableVertexAttribArray(texAttrib);
glVertexAttribPointer(texAttrib, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); // 6 offset from beginning
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