Non-changing value of transmitter

We have a 4-20mA analyzer transmitter with range of 0-5mg/L chlorine. The AI card is Siemens 6ES7 331-7KF02-0AB0, and the chlorine process operation point is about 0.01 mg/l. Our WinCC faceplate shows a non-changing value of 0.15 or 0.12 for a long time. I checked the related DB value and it was (ex. 0.1524XXXXX) and the X figures were changing and the first four figures were fixed. The AI resolution setting is 27684. I need help.