OK, the RenameTo in the Library looks like it only moves in the same directory. This one will work anywhere (That you have the correct access rights to)
B4X:
'Renames the file denoted by this pathname.
Public Sub RenameTo(DirName As String, FileName As String, NewDirName As String, NewFileName As String) As Boolean
Dim Source As JavaObject
Source.InitializeNewInstance("java.io.File",Array(DirName,FileName))
Dim Dest As JavaObject
Dest.InitializeNewInstance("java.io.File",Array(NewDirName,NewFileName))
Return Source.RunMethod("renameTo",Array As Object(Dest))
End Sub
Sub RenameFolder(Parent As String, CurrentFolder As String, NewFolder)
Dim p As Phone
Dim args(2) As String
args(0) = File.Combine(Parent, CurrentFolder)
args(1) = File.Combine(Parent, NewFolder)
p.Shell("mv", args, Null, Null)
End Sub