title: Count distinct not working in pyspark 3.2.1
body: <p>just trying with simple count distinct function  and it is giving error while running it</p>
  <pre><code>    df = edco_sales.agg(countDistinct(&quot;store_cd&quot;))
      return df
  </code></pre>
  <p>test_1  |     df = edco_sales.agg(countDistinct(&quot;store_cd&quot;))
  test_1  | /usr/local/lib/python3.7/dist-packages/pyspark/sql/functions.py:991: in countDistinct
  test_1  |     return count_distinct(col, *cols)
  test_1  | /usr/local/lib/python3.7/dist-packages/pyspark/sql/functions.py:1008: in count_distinct
  test_1  |     jc = sc._jvm.functions.count_distinct(_to_java_column(col), _to_seq(sc, cols, _to_java_column))</p>
  <p>does anyone know what possible issue is with above code or why count distinct is giving error</p>