Hello,
The problem could be in three places:
1) the Floorboard
2) the CAT 5 cable
3) the CAT 5 jack on the amp.
Try your floorboard on a different Line 6 amp with a different cable to see if this changes anything. If so, narrow down the variables unit you find the problem unit and get it repaired. See the following link for more information:
Line 6 Floorboard and FB4 F.A.Q.
http://line6.com/community/docs/DOC-1854
Please let us know if you need further assistance, or close out the ticket as “answered” if your situation has been resolved.