You need to close your StreamWriter when you are done. sw.Close
You must call Close to ensure that all data is correctly written out to the underlying stream.
Better yet, use Using. The following would go inside your if:
Using sw As New StreamWriter(fileLoc)
sw.Write("Test line write")
For rowcount As Double = 1 To rows
For colcount As Double = 1 To cols
'when the file write test works I will finish the rest of the code here
Next
Next
End Using
This will automatically dispose of the StreamWriter for you.