NSButton setImage not working

Question

I am trying to change the image of my nsbutton for my application. I have searched and found a couple of ways to do so but none of them are working for me at the moment.

I have looked at the following solutions :

How to set NSButton background image Using -setImage on NSButton

I have a routine that is called when I click the button :

- (IBAction)pauseResumeButtonAction:(id)sender

{ IAgentInterface* agentInterface = ioc::Container::Resolve();

if (self.pauseResumeSwitch == PauseResumeSwitch::PAUSE)
{
    //if ready to pause do this
    AgentCommand cmd( AGENT_CMD_PAUSE_SERVICE);
    agentInterface->sendAgentCommand( cmd );
    self.pauseResumeSwitch = PauseResumeSwitch::RESUME;

    [self.pauseResumeButton setImage:[NSImage imageNamed:@"pause.png"]];
}
else if (self.pauseResumeSwitch == PauseResumeSwitch::RESUME)
{
    //else if ready to resume do this
    AgentCommand cmd( AGENT_CMD_RESUME_SERVICE);
    agentInterface->sendAgentCommand( cmd );
    self.pauseResumeSwitch = PauseResumeSwitch::PAUSE;

    [self.pauseResumeButton setImage:[NSImage imageNamed:@"resume.png"]];
}

}

can someone please help me find my mistake ? it will be of great help

thanks in advance :)