I'll installing a 3560 switch unto our LAN. I'm replacing a 2950 switch. I removed the old switch & placed the new 3560 in the cabinet. Plugged in everything. Lastly I plugged in the up link port. Using Fibre LC-ST but I have no Link light flashing. All devices on this switch is not getting any connectivity. What do I have to check for? please have help urgently. do know what to check next???