Binding A Field To Specific Column In A Pull Down Manue

I created a a table with multiple columns. For example the table looks like as follows:

Table name - Observationcode
Code Value Description
CCH 1000 Heavy Crack
CCM 750 Medium Crack
CCL 500 Low Crack

I created fields on the subform - frmsubmain1
Field names are as follows:

Observation Code
Value
Description

I created combobox for a field called "observation code" so that the above mentioned table "observationcode" appear as a pull down menu to select from multiple lists. In the property section I bound the feild "Observation Code" to " column 1" to record the item in the column 1. I reapted this process for the fields "Value" but this time I bound the field to column 2 to show the value rate or value for the selected code. Again I reapeated this process for field name called "Description" but this time I bound the column to the column 3 to record the description for the corresponding code.

On the main form - frmmain

I created a field called Rate to calculate the total value in the subform "frmsubmain1" the validation rule looks like as follows:
=sum(Forms![frmsubmain1]![Value])

None of these seems like working except for the first one "Observation code". Observation code is looking into the right column and registering the right code but not the other two fields are not looking to the right columns, instead they are looking into the firts coloumn. I don't know why. Can anyone help me resolve these issues. I appreciate your help. Thanks.

Girma