Sort is not working as I was expecting

[iscar_marius]

I tried to use below code:

          Worksheets("Input").Range(Cells(17, 1), Cells(number_row, 8)).Sort _
            Key1:=Worksheets("Input").Range("A17")

to sort this kind of data:

test1
test2
....
test10
test11
...

The result is like this:
test1
test10
test11
test2
...


But I need :
test1
test2
....

How can I do this with sort?
Thank you.