Consolidation Of Worksheets Using VBA Code

I have many sheets in an excel workbook. Each sheet contains some data. I want data of all sheets into one sheet in the same workbook. The data of sheet 3 should appear below the data of sheet 2 & so on. I leave the first sheet of the workbook blank so that data of remaining sheets can be consolidated in the first sheet. Therefore I wrote the following code:

Public Sub consolsheets()
Dim a As Integer
Dim rng, rng2 As Range
a = a + 1
For a = 2 To Worksheets.Count
Worksheets(a).Activate
Set rng = Worksheets(a).UsedRange
rng.Copy

[code].....

Data of row 3 of sheet 2 (ccccc) is overwritten by data of row 1 sheet 3 (11111). Similarly, data of row 3 of sheet 3 (33333) is overwritten by data of row 1 of sheet 4 (@@@@@).

This problem is not faced if the sheet 1(blank sheet) has some data.