I am trying to retrieve an application setting but an empty string is being returned on a Windows FormApplication

string importFile = System.Configuration.ConfigurationManager.AppSettings["CSVFile"];
MessageBox.Show("Import File = " + importFile);

My MyApp.Exe_Config is:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
        <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="MYEXE.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
        </sectionGroup>
    </configSections>
    <applicationSettings>
        <MYEXE.Properties.Settings>
            <setting name="CSVFile" serializeAs="String">
                <value>This is a CSV File Setting</value>
            </setting>
        </MYEXE.Properties.Settings>
    </applicationSettings>
</configuration>

Any ideas of what could be wrong.
TIA, Gerard