BLANK VALUE IN SSRS BUT DATA IN SQL QUERY - reporting-services

Question

I'm working in a solution in SSRS that it's driving me crazy, I will explain it a bit before shows you my problem:
Select 25 data values from a table with analog input data (from current, voltage, pressure, etc. tags) using parameters #startDate = yeterday 6am and #EndDate = today 6am. Now we have a table with 25 values from 6am to 6am from different tagID's.
My problem starts when just one tagId of 16, it's showing me in the SSRS presentation values 0.0000 when in the Sql output shows me -0.00548...
For practical purpouses I will just use 2 tagIds (MSF_PDI_003, MSF_PDI_004)
Here the SQL Query:
declare #startDate datetime2 = '2017-04-19 11:00',
#endDate datetime2 = '2017-04-20 11:00';
SELECT InstaTime,
MSF_PDI_003,
MSF_PDI_004
FROM (
SELECT
DATEADD(HH,-5,H.time) AS InstaTime,
SUM(
CASE
WHEN t.tagName = 'analog.MSF_PDI_003.curval'
Then H.value
ELSE 0
END) as MSF_PDI_003,
SUM(
CASE
WHEN t.tagName = 'analog.MSF_PDI_004.curval'
Then H.value
ELSE 0
END) as MSF_PDI_004
FROM hour H
INNER JOIN tag T
ON T.tagId = H.tagId
WHERE T.tagName IN
('analog.MSF_PDI_003.curval', 'analog.MSF_PDI_004.curval')
AND H.time >= #startDate
And H.time <= #endDate
GROUP BY time
) QueryData
order by InstaTime desc
And this the result of the query:
SQL QUERY RESULT IN SQL-SERVER
And these are the expressions that I'm using in the textboxes of the tablix in the SSRS (I used a test dataset for this query: summary_prueba)
=Fields!InstaTime.Value
=Fields!MSF_PDI_003.Value
=Fields!MSF_PDI_004.Value
And here the results of the table in SSRS:
CLICK IMAGE: SAMPLE2 SRSS
What could be the problem around here?
* Is the Only one with negative values, could be forcing a round? Something about a different format I should use?
Driving me nuts and can't find what's wrong. I tried to change the format and is the same, can you guys please help me? Because this thing doesn't let me sleep at night, I'm starting to have nightmares lol.
I'm using SQL Server 2012, and for the report MS Visual Studio Shell 2010.

Answer 1

Let's start by consolidating your query into one statement, instead of the UNION and separate SELECT SUM(...) that you have now:
declare #startDate datetime2 = '2017-04-18 11:00',
#endDate datetime2 = '2017-04-19 11:00';
SELECT InstaTime,
MSF_PDI_003,
MSF_PDI_004
FROM (
SELECT
DATEADD(HH,-5,H.time) AS InstaTime,
SUM(
CASE
WHEN t.tagName = 'analog.MSF_PDI_003.curval'
Then H.value
ELSE 0
END) as MSF_PDI_003,
SUM(
CASE
WHEN t.tagName = 'analog.MSF_PDI_004.curval'
Then H.value
ELSE 0
END) as MSF_PDI_004
FROM hour H
INNER JOIN tag T
ON T.tagId = H.tagId
WHERE T.tagName IN
('analog.MSF_PDI_003.curval', 'analog.MSF_PDI_004.curval')
AND H.time >= #startDate
And H.time <= #endDate
GROUP BY InstaTime
) QueryData
order by InstaTime desc
Now, if there is no matching 004 or 003 value, they will report as zero instead of being blank. Try this, and see whether this matches what you need.

Answer 2

All right I found a solution but not the problem, because I still don't understand why if in the sql server I can see data and in the QueryDesigner of SSRS I still have 0.00 values.
This is a relational DB, I use 2 tables, from the same database
DB: Timeseries
Table1: hour, from here I use value,time,tagId
Table2: tag, from here I use tagName,tagId
Both have tagId in common, but I just realized that exaclty just this signal MSF_PDI_004 it's not related to the tagName in the table tag.(Have to be an error when created that signal)
I changed the Query and instead of use the tagName I used the tagId, and everything was fine, I could see the same values in SSRS than I was seeing in the SQL SERVER.
Still I think its strange, because if the query works on SQL SERVER, why should not be transparent for the SSRS?
I hope somebody can explain me this, thank you for the ones who took time for read and help.