Phone NOT detected

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http://forum.xda-developers.com – Hi I have updated drivers for GS4 SPH L720, changed cables and also have ticked USB debug. cant seem to see phone or my sd on my comp. if i switch from S4 to S3 it detects. tried to ROOT my phone using qbking's video, have managed to inject files using his method, which proves the link between my phone and comp. just cant see the phone nor my sd under my computer. can anybody help or advice. (HowTos)