Thank you for a great answer. I'll use your advise and do sorting in dataset. I should make it on my own so i won't be bothering you with a...

Thank you both for your replies.
There are records in DatabaseTable and insert works fine, i've checked. So i guess that Phil Parkin answer is more suitable in this case.

So, today the same situation as yesterday. No errors when generating report under VisualStudio, error ("Error: Subreport could not be shown.") when running report with Report Server. 
I've attached an...

Very helpful link. One more time, thank you very much!!

Thank you for replying.
I'll try to look at log but i don't have direct access to it. I need to ask admin for a log but for sure your...

So, it's that simple. Man i feel stupid 🙂
Thank you for quick reply!

Thank you for replay. I've read that article you attached but know i wonder, what determines the subreport size, draft of a subreport or generated subreport with pages filled?

Sorry for so late answer but i have a good reason to be quiet as a became a father for the second time on the 29.06.2017 🙂 Hurray!!!:)
So after...

I've checked "Column names in the first data row" in a flat file connection manager, so that's not the issue:/

Thanks for a quick replay!
Here are my thoughts:
1. I've tried to add new column and replace BirthDate column. Both methods failed. 

2. I am working with SQL Server...

I haven't mentioned earlier but i would like to do all needed conversion in SSIS, like in derived column component.
It seemed to me like a simple task, import data...

I need DATE output.

Thank you for answers!
I've tried to apply Phil's solution but i still have problems with appropiate conversion but to be honest i coludn't spent as much time on it...

Thank you for reply. I had to do something with this problem so i came up with following solution.
I have added a row that holds value for missing group...

Thank you for reply. Your assumption is right, i don't see group number 3 because i don't have any data for that group.