Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE functional_areas ( functional_area_code VARCHAR, functional_area_description VARCHAR )
TABLE: CREATE TABLE documents ( access_count INTEGER, document_code VARCHAR )
TABLE: CREATE TABLE document_functional_areas ( document_code VARCHAR, functional_area_code VARCHAR )

### Question ###
Find the average access counts of documents with functional area 'Acknowledgement'.

### Accurate SQL ###

SELECT AVG(t1.access_count) FROM documents AS t1 JOIN document_functional_areas AS t2 ON t1.document_code = t2.document_code JOIN functional_areas AS t3 ON t2.functional_area_code = t3.functional_area_code WHERE t3.functional_area_description = "Acknowledgement"