image Path Not Working in Sub Root Directory in Asp.net

Hi,

i am use in Asp.net Master Page below Description.

• Images/Demo/
• Main.Master
• Dem.Aspx
• Category folder Name
• Cate.aspx form Name in Category Folder use in main .Master Page refernce

Display Header Image in Dem.aspx page but not Display in Cate.aspx Page 

Add Image in Code Behind.

Me.MenuItem2.Style.Add("background-image", "url('imagas/head/header_06.jpg'")
Me.MenuItem2.Style.Add("background-repeat", "repeat-x")

only Display In Root Directory not Working in Sub Root Directory.

Pls Solved Any Budy Help me.

Thanks.