I suppose that behind Field() collection there are some member you omitt, which VB automaticallu recognizes. Try to type point behind Fields() and see if IntelliSense will show some member like Value, etc. For example:

thisform.elb1.Object.Field("PARTNO").Value = "123456"
thisform.elb1.Object.Field("COLOR").Value = "Green"

I also put "Object" in these rows; there are situations in VFP, in which this also was solve some problems.