A few points...
I wouldn't use Filename as a variable name ... GetOpenFilename will return a Full Path as required in the Workbooks.Open command whereas when using Windows(name) you require just the filename (as you use later for the other file)
... it's not clear whether the Rogin Pareto1.xls is the workbook in which the code resides ... I'm assuming it is... does the following help:
Note: when you open a workbook it immediately becomes the activeworkbook so you don't actually need to run the Activate command
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