Need help in Updating tqble and getting error2001?

[pukhton]

I am getting this error each time I run my form in Access.
I have a table calls "Medications" and it has three colums (Medication_Name, Concentration, Units) then I have another table name Main Table, which grabs the value from the Form and put it in MainTable under Medication_Name, Concentration and Units.

On the form I have a combo box for Mecdication, When User picks MEDICATION the concentration and Units text box get populated by it self. I have a small query for it.

SELECT Medications.Concentration, Medications.Units
FROM Medications
WHERE (((Medications.Medication_Name)=[Forms]![frmMain]![Medication_Name]));
 

In code thats what I have to fetch the value from the Medications Table and get Concentration and Units Textbox populated, but the problem is the value from Concentration and Units are not getting enterd in the MainTable.
The control source for Concentration is

 =DLookUp("Concentration","medquery")

and for the Unit is

 =DLookUp("Units","medquery")

Private Sub Medication_Name_Change()
 
'DoCmd.OpenQuery "medquery"
  Me!Concentration.Requery
End Sub
 

I would appreciate if some one cal help me out.
Thx.

[pukhton]

I am not getting any luck, i have tried everything. anybody please?

[MMcCarthy]

I;m sorry but I'm totally confused about what you are doing.

Firstly, why do you have the same fields in two tables?

Secondly your DLookup queries don't have any criteria set but they can only return one value.