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.