Hello guys. I have made a Periodic Table. I have put 112 elements ( with buttons ) on it , and for each element ( button ) i used the events: Mouse_Enter & Mouse_Leave.

Mouse_Enter - in my picturebox8 , appears an image
Mouse_Leave - in my picturebox8 , dissapears the image

Ok , for 97 elements ( buttons ) this 2 events work , but for the last 15 elements ( named as Actinoids ) don't work.

The pictures for picturebox8 i load them from Resources , and the code for all 112 elements looks like:

private void Button99_MouseEnter(object sender, EventArgs e)
            pictureBox8.BackgroundImage = Properties.Resources.Uraniu_img; // Or other
        private void Button99_MouseLeave(object sender, EventArgs e)

As i mentioned up , for all 112 elements i have this , but for last 15 this code don't works ( the picture doesn't appears in picturebox8 ).

This are the elements which don't works: http://a.yfrog.com/img265/530/twork.png

A element which work when i go with the mouse on it , do this: http://a.yfrog.com/img444/2532/work.png

Another problem must be the size ?

The elements which works have ~ 4 - 6kb's , and elements which don't works have ~10kb's


And btw , i have to mention this -> In my resources folder i have 191 images xD ... Can this too to be a problem ?