All,
dhxform_dhx_skyblue/dhxform_chbxrd.gif seems to be different in version 3.6 build 131108.
I found that when a radio control was selected the image would go away. It seems to be because the CSS is telling the div to use a piece of this image at -180px. Unfortunately, the image in the new build is only 144px wide so it will display nothing.
To fix, I simply grabbed the image from the previous build (at lease the previous one I had) and coped it forward. This image is 216px wide.
Hello
Try to replace this file with the attached one
Darya,
The image you have posted is the wrong one. As I stated, the CSS points to this image at -180px. This image is only 144px. Please remember that CSS starts counting from the bottom right.
The file I am attaching is the correct one. Upon further investigating of the build 131108 download, it is only incorrect within the dhtmlx_pro_full.zip file.
Oh, sorry… I wanted to attach the file you have attahed - have mixed pathes 
But how we can reproduce this issue?