custom configuration file icon for Mac is not showing. i think it might be an plist issue

Question

i am working application ABC where user can save configuration. Then later it can be open using same file. but when i am saving this configuration file. its not showing the icon.

the application is built using qt c++..

here is my plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleExecutable</key>
    <string>ABC</string>
    <key>CFBundleDocumentTypes</key>
    <array>
    <dict>
    <key>CFBundleTypeName</key>
    <string>abc</string>
    <key>CFBundleTypeIconFile</key>
    <string>abc.icns</string>
    </dict>
    </array>
    <key>CFBundleIdentifier</key>
    <string>com.########.####</string>
    <key>CFBundlePackageType</key>
    <string>APPL</string>
    <key>CFBundleSignature</key>
    <string>????</string>
    <key>NOTE</key>
    <string>This file was generated by Qt/QMake.</string>
    <key>CFBundleIconFile</key>
    <string>ABC.icns</string>
    <key>IFPkgFlagRestartAction</key>
    <string>RecommendedRestart</string>
    <key>IFPkgFlagAuthorizationAction</key>
    <string>RootAuthorization</string>
    <key>NSPrincipalClass</key>
    <string>NSApplication</string>
    <key>NSHighResolutionCapable</key>
    <string>True</string>
</dict>
</plist>`

what is the possible cause?

i tried directly providing path of icon in plist. i tried CFBundleSignature from ???? to ABCC