Excel Spreadsheet access from other Spreadsheet

[ExcelNoob1996]

Hey Guys,
What i basically want to do is the following:

i have a huge chunk of data (Data!) in one spreadsheet and want to choose one specific Collumn from where to add the sum. Here comes the trick: i dont want the specific collumns to fixed i want them to be able to change for example from I to K which is already possible to be switched in the Conclusion! spreadsheet now i want go ahead in the Conclusion spreadsheet and add everything in Data with the collumn deposited also in Conclusion as C8 with the value 1. I´ve already tried it like this: =SUMIF("Data!"&Conclusion!C8;1).
But that doesn´t really work
Has someone got any ideas?
Thanks in advance

EDIT: Here some visual addition to my issue:

A	B	C	D
Adress	More	Test	Example

<tbody>
</tbody>

this is the Spreadsheet with the data chunk

	A	B	C	D	E	F	G	H
1	Collumn:	A:A
2	=SUMIF("Data!"&Conclusion!B1;1)
3
4
5
6
7
8
9

<tbody>
</tbody>

 

[JonXL]

=IFERROR(SUM(INDIRECT("Data!"&B1&":"&B1))+1,"")

In B1, just enter the letter of the column (the formula will adjust the reference to include the colon) - for example, entering I will reference Data!I:I.

 

[ExcelNoob1996]

Thank you that worked perfectly