SQL: PIVOT return all NULL values - sql

Question

Hello everyone and thanks in advance.
I have two tables that I need to merge using Pivot.
1)Table with list of users:
#Tbl_staff(UserId INT,
Name NVARCHAR(MAX),
Surname NVARCHAR(MAX),
Level NVARCHAR (MAX)
)
2) Table with users' actions:
#Tbl_acts(Day DATE,
UserIdfk INT,
WorkedHours NVARCHAR(MAX),
Absence NVARCHAR(MAX),
Festivity NVARCHAR(2)
)
Table 2 has a complete month for each ID and for each day the action recorded. (Hours worked, hours of absence and type of absence, if the day is a holiday)..
It can also be null if in the db there is no action for that person on that day.
I wrote my Pivot like this:
DECLARE #columns NVARCHAR(MAX), #sql NVARCHAR(MAX);
SET #columns = N'';
SELECT #columns += N', p.' + QUOTENAME((cast(USERID AS VARCHAR(MAX)) + ' ' + NAME+ ' ' + SURNAME+' ' +(ISNULL (LEVEL,''))))
FROM (SELECT p.USERID,p.NAME,p.SURNAME,p.LEVEL FROM #TBL_STAFF AS p
INNER JOIN #TBL_ACTS AS o
ON p.USERID = o.USERIDFK
GROUP BY p.USERID,P.NAME,P.SURNAME,P.LEVEL) AS x;
SET #sql = N'
SELECT DAY,' + STUFF(#columns, 1, 2, '') + '
FROM
(
SELECT DISTINCT o.DAY,IDU = CAST(p.USERID AS NVARCHAR(MAX)), o.WORKEDHOURS
FROM #TBL_STAFF AS p, #TBL_ACTS AS o
where p.USERID= o.USERIDFK
) AS j
PIVOT
(
MAX(WORKEDHOURS) FOR IDU IN ('
+ STUFF(REPLACE(#columns, ', p.[', ',['), 1, 1, '')
+ ')
) AS p ORDER BY DAY;';
PRINT #sql;
EXEC sp_executesql #sql;
(Trying to show only the worked hours ... would be a good start)
It's the result: Column 'day' is ok(31 rows) and 'staff' too but it shows nothing inside it.