Please can someone help me with a sorting machine problem

[Andrew Baldacchino]

I have a sorting machine with 10 redpower sorters, but certain items don't sort correctly

eg:

Rubber tress logs

insulated redstone wire (all colours)

saphires

rubys

emeralds

(to name but a few)

The items come out of the sorting machine tagged with the colour i have specified (yellow) in the GUI for sorting machine but when they pass the pneumatic tube with the corresponding colour, they do not flow up it and so carry on along the same path that the items with the default tag (white) follow.