Tag is not defined, when it has been manually created?

I have three tags, all under a UI category, so the tags are called:

UI/SpeedText

UI/GearText

UI/rpmMeter

Here is a piece of my script:

void Start(){
		Car = GetComponent<Rigidbody> ();
		SpeedText = GameObject.FindWithTag ("SpeedText").GetComponent<Text> ();
		gearText = GameObject.FindWithTag ("GearText").GetComponent<Text> ();
		rpmMeter = GameObject.FindWithTag ("rpmMeter").GetComponent<RectTransform> ();
		float Average = (MaxGrip + MinGrip) / 2;
		TurnLowValue = Average * MaxTurnSpeed * 5;
		TurnHighValue = TurnLowValue * 6;
		multiplierValue = 1 / MaxGrip;
	}

Strangely, it is able to find SpeedText and GearText, but it says that rpmMeter is not a defined tag. It is worth noting that if I remove UI before it so that the tag is just rpmMeter, it is able to function properly.

I have found the problem. The tag must be written as “UI/rpmMeter”, and the reason the thee tags worked is that they somehow were duplicated, and the game objects had the tag without UI. Thanks everyone for your help!