Input.GetKeyDown don't work.

Hi. So i have this small function it called from gui button.“SaveP” part is working fine,but part with Input not working at all.I don’t have any errors it’s just not working.What am I doing wrong here? Thank you.

public void OnSavebutton()
	{
		//InputF = GameObject.Find ("CarNameEnter");
		SaveP.SetActive (true);

		if (Input.GetKeyDown (KeyCode.Return)) {
			InputField inp = InputF.GetComponent<InputField> ();
			CarName = inp.text;
			test = true;
		}


		 
	}

hi;
u have to put Input.GetKey into Update method cause it need to check every frame if its pressing or not ;