Field on custom table not searchable in selector lookup but the other two work

I have a custom table which is used for a selector on my extension of the PMTimeActivity graph.

When you click the lookup, you can see there are two records to choose from:

If you type “122”, you can see it finds the first record in the Plan Code field:

If you type “es”, if highlights both of the records in the Description column:

If you type “fs” I want it to show the first record in the selector as that has “FSDF” in the Alternate Plan Code column.

These are the pertinent DAC fields for the custom table

       #region PlanCD
        [PXDBString(50, IsUnicode = true, IsKey = true, InputMask = ">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")]
        [PXDBDefault]
        [PXUIField(DisplayName = "Plan Code", Required = true)]
        [PXCheckUnique(typeof(ICSPlan.planCD))]
        public virtual string PlanCD { get; set; }
        public abstract class planCD : PX.Data.BQL.BqlString.Field<planCD> { }
        #endregion

        #region LegacyPlanCD
        [PXDBString(50, IsUnicode = true, InputMask = ">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")]
        [PXUIField(DisplayName = "Alternate Plan Code")]
        [PXDBDefault(PersistingCheck = PXPersistingCheck.Nothing)]
        [PXCheckUnique(typeof(ICSPlan.legacyPlanCD))]
        public virtual string LegacyPlanCD { get; set; }
        public abstract class legacyPlanCD : PX.Data.BQL.BqlString.Field<legacyPlanCD> { }
        #endregion

        #region Description
        [PXDBString(256, IsUnicode = true)]
        [PXDBDefault]
        [PXUIField(DisplayName = "Description", Required = true)]
        public virtual string Description { get; set; }
        public abstract class description : PX.Data.BQL.BqlString.Field<description> { }
        #endregion
 

This is the DAC extension field used for the selector

        #region UsrPlanCD
        [PXDBString(50, IsUnicode = true)]
        [PXUIField(DisplayName = "Plan ID")]
        [PXSelector(typeof(SearchFor<ICSPlan.planCD>.Where<ICSPlan.active.IsEqual<True>>),
                typeof(ICSPlan.planCD),
                typeof(ICSPlan.legacyPlanCD),
                typeof(ICSPlan.description),
                SubstituteKey = typeof(ICSPlan.planCD),
                DescriptionField = typeof(ICSPlan.description))]
        public string UsrPlanCD { get; set; }
        public abstract class usrPlanCD : PX.Data.BQL.BqlString.Field<usrPlanCD> { }
        #endregion
 

Any ideas what I need to do to make the Alternate Plan Code column searchable in the selector?  Is my DAC extension and DAC setup properly?