uv does't apply correctly

Hey I've programmed a procedudural mesh generation like minecraft. At the moment I use 2 Textures on 1 material for some testig stuff. So currently I have 2 different types of blocks in my game but the textures won't apply correctly. It looks like this:

It looks like there's a pixel missing. (the white stripes) The textures wrap mode is set to clamp and in Photoshop are no missing pixels in the texture.

This is the texture I use:

And here is my code to apply them to the mesh:

     public void GenerateFace(byte block, Vector3 vert1, Vector3 vert2, Vector3 vert3, Vector3 vert4)
     {
         int index = vertices.Count;
 
         vertices.Add (vert1);
         vertices.Add (vert2);
         vertices.Add (vert3);
         vertices.Add (vert4);
 
         triangles.Add (index + 0);
         triangles.Add (index + 1);
         triangles.Add (index + 2);
         triangles.Add (index + 3);
         triangles.Add (index + 2);
         triangles.Add (index + 1);
 
         Vector2 uvWidth = new Vector2(0.5f, 0.5f);
         Vector2 uvCorner = new Vector2((block - 1f)/2, 0.5f); //the left bottom corner of the tile
 
         uv.Add (uvCorner);
         uv.Add (new Vector2(uvCorner.x + uvWidth.x, uvCorner.y));
         uv.Add (new Vector2(uvCorner.x, uvCorner.y + uvWidth.y));
         uv.Add (new Vector2(uvCorner.x + uvWidth.x, uvCorner.y + uvWidth.y));
     }

Maybe I'm doing something wrong here? If you have some ideas pleas let me know ;)