Range in Remove duplicates

I have a block consisting of 25 columns, 500-600 rows and a unique identifier in Col A. Sometimes I need to remove duplicates and I have tried this, but it does'nt work:

Selection.End(xlDown).Select
bot2 = ActiveCell.Row

' some other code

Set hele = Range(Cells(2, 1), Cells(bot2, 25))
Range(hele).RemoveDuplicates Columns:=1

so instead I have this line:

Range("a1").RemoveDuplicates Columns:=1

and it works regardless of what I have put in as Range as long as it is a single cell in the worksheet.

What is the purpose of defining the Range?

NSV

PS: If someone can tip me with a more elegant way of defining the number rows, I'd appreciate it.