reading from app.config file

I am trying to read StartingMonthColumn and CategoryHeadingColumn from the below app.config file using the code

ConfigurationSettings.AppSettings["StartingMonthColumn"]

but it is returning null, also ConfigurationSettings.AppSettings.Count returns zero

Please help me to read this in my windows application

<configuration>
    <configSections>
        <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="CTARepository.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
        </sectionGroup>
    </configSections>
    <userSettings>
        <CTARepository.Properties.Settings>
            <setting name="Setting" serializeAs="String">
                <value />
            </setting>
        </CTARepository.Properties.Settings>
    </userSettings>
    <appSettings>
        <add key="StartingMonthColumn" value="7"/>
        <add key="CategoryHeadingColumn" value="1"/>
    </appSettings>
</configuration>