AddRow function does not update primary key field of infotable on ThingWorx

I am using the AddRow function to update an infotable.

It is copying values into all other fields except the primary key field.

Kindly advise me on how to correct this. See code snippet below and attached screenshot of the infotable.

// Get a direct reference to the infoTableProperty on the entity
var Pump_Curves = me.Pump_Curves;
// Create a new NamedVTQ entry object to add to the infotable
var newEntry = new Object();
newEntry.Delta_P = 1.87; // primary key
newEntry.RPM_700 = 14;
newEntry.RPM_800 = 15;
newEntry.RPM_900 = 1.2;
newEntry.RPM_1000 = 2.1;
newEntry.RPM_1140 = 5;
newEntry.RPM_ACT = me.F1; // Current flowrate
Pump_Curves.AddRow(newEntry);