Data uodate in Subform (1 Viewer)

[Harry_38]

Access 2010:
Mainform (Table with persons)
subform1 (table with course participants)
subform2 (Bank book table)

In the mainform, I select a person "XX"
Next I see in subform1 the courses of 'XX' and the amount due for each course.
In subform2, I note the amount received for a particular course. Next, after update the amount: amountdue= amountdue - amount received
In VBA: Forms!Mainform!Subform1!Due = Forms!Mainform!Subform1!Due - [amount received]
Doesn't work. VBA can't find subform1
Please help, where do I go wrong?

 

[Harry_38]

I found that the name in de querry listing differed for the name in the property screen of that query. One should use Property name.
problem solved