if Dir("C:\Program Files\Adobe\Reader 8.0\Reader\acroRd32.exe" & Chr(34) & CHEMIN & A$)<>"" then
On Error Resume Next
rc = Shell(Chr(34) & "C:\Program Files\Adobe\Reader 8.0\Reader\acroRd32.exe" & Chr(34) & CHEMIN & A$, vbNormalFocus)
Else
MsgBox ("fichier inexistant")
End If