Binding a Command to an Input Gesture

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C#

WPF

Hello,
i bound a InputGesture to a Command, which partly works.
looks as Follows:

Code Behind:

public static RoutedCommand myCommand = new RoutedCommand();
private void MyCommandExecuted(object sender, ExecutedEventArgs e)
{
    MessageBox.Show("Test");
}

<UserControl.CommandBindings>
<CommandBinding Command="var:UserControlName.myCommand" Executed="MyCommandExecuted">
</Usercontrol.CommandBindings>

<USerControl.InputBindings>
<KeyBinding Command="var:UserControlName.myCommand" Key="A">
</USerControl.InputBindings>

This command is also assigned to a button in the user Control. if i run my project, an press "A" on the Keyboard, nothing Happens. if i Press the Button, the Message Box appears. After once pressing the Button, also the Keyboard Key works. if i now press "A" again, the messageBox appears too.

Why do i i have to press the Butten once first, before i can use "A"?? What am i doing wrong?

thx for help

kind regards Moti