Yes, the filesize works fine now. Thank you very much for your help

The problem I have now is that I get an overflow error when I use the code below as a test and reach the 2GB.

I get the error on the line: "PosL = Position And &HFFFFFFFF" in the API_ReadFile sub. I tried to change some things myself, but I keep getting the overflow error.

Code:
Private b(9727999) As Byte

Private Sub Command1_Click()
Dim sString As String, cCount As Double, i As Long

Do Until i = 470
    i = i + 1
    
    API_ReadFile File_Num, cCount, 9728000, b()
        
    cCount = CDbl(cCount) + CDbl(9728000)

DoEvents
Loop
End Sub