Forms :: Populate Textbox After MULTIPLE Combobox Selection

Got a bit stuck in a database. I have a form based on a query. On the form I have 4 comboboxes.

The combo boxes filter eachother without a problem (based on custom select query)

Now I want after the fourth combobox value is selected, I want to populate a text field with a value from a different column from the master query (after the 4 selections only 1 value should be possible)

Master query contains 5 columns:
- group
- type
- job
- insurance
- charge

combo1 selects group (and filters records)
combo2 selects type (from remaining records and filters again)
combo3 selects job (from remaining records and filters again)
combo4 selects insurance (from remaining records and filters again)

Combo4 is based on following query:
-column1
Insurance
Total=Group by
Show=yes
-column2
Job
Total=Where
show=no
Criteria [forms]![name].[combo]

This works great and the dropbox only shows 1 OF EACH DIFFERENT record

If I add a text box and want to see the "charge" value, that I thought I could use the ME.text-code. But in order to do this, I have to add the charge column into the query of Combo4.

If I do this, the dropbox for insurance gives me multiple values that are the same. Is there any way to make this work?