custom field not populating

I have added a custom field it is perfectly able to save the data in my table but when I open that record to edit field is always empty. What am I missing here ?

namespace PX.Objects.CR
{
    public class CROpportunityExt : PXCacheExtension<PX.Objects.CR.CROpportunity>
  {
        #region UsrProbability
        [PXDBInt]
        [PXIntList(
            new int[]
            {10,20,30,40,50,60,70,80,90,100},
            new string[]
            {"10%","20%","30%","40%","50%","60%","70%","80%","90%", "100%"})]
        [PXUIField(DisplayName = "Probability")]

        public virtual int? UsrProbability { get; set; }
        public abstract class usrProbability : PX.Data.BQL.BqlInt.Field<usrProbability> { }
        #endregion
    }
}