Visual Basic.NET - Error con API de windows

Buenas tardes,

usando el siguiente codigo:

Public Function IniGet(ByVal sFileName As String, ByVal sSection As String, ByVal sKeyName As String, Optional ByVal sDefault As String = "") As String

Dim ret As Integer
Dim sRetVal As String
'
sRetVal = New String(Chr(0), 255)
'
ret = GetPrivateProfileString(sSection, sKeyName, sDefault, sRetVal, Len(sRetVal), sFileName)
If ret = 0 Then
Return sDefault
Else
Return Left(sRetVal, ret)
End If
End Function

Me da error de desbordamiento, incluso poniendo la variable de tipo Long.

Agradezco su ayuda.

attte

Willians