SQL stored procedure throwing invalid in the select list error

I am converting from mysql to sql server.

While converting a select stored proc,

CREATE PROCEDURE selPropertyByAcntID
(
@in_acntID INT
)
AS
SELECT *
     , SUM(CASE
                        WHEN u.prop_id IS NOT NULL THEN 1
                        ELSE 0
                 END) AS UnitCount
FROM 
    prop_details d
INNER JOIN 
    acnt_property a
ON 
    d.prop_id = a.prop_id
LEFT JOIN 
    unit_details u
ON 
    d.prop_id = u.prop_id
WHERE 
    a.group_id = @in_acntID
GROUP BY 
    d.prop_id;

It is throwing the following error:

Error: 8120 Severity 16 Column 'prop_details.prop_title' is invalid in the select list because it is not container in either an aggregate function or the GROUP BY clause.

strange -- the exact same stored proc isworking in a mysql environment.

Any help on this is much appreciated.

Copyright Notice：Content Author:「Rick」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/8431727/sql-stored-procedure-throwing-invalid-in-the-select-list-error