I suspect that the path name is not making it to your mini-package.
Since the error message says "The system cannot find the path specified," I would put a popup in your mini-package that displays the path it is using so you can confirm that it is being passed the correct path.
Here is the code to pass the global variable to the mini-package:
Dim PathVariable As String = Dts.Variables("PathVariable").Value.ToString
Here is the code for the popup to display the path:
Dim button As DialogResult = MessageBox.Show(PathVariable, "PathVariable", MessageBoxButtons.OK)