I thought i was going mad, but a short break solved the problem !!

It was operator error. I messed up the numbering system on the IDC header.

I had the numbering system as


1 6
2 7
3 8
4 9
5 10

When it actually is:

1 2
3 4
5 6
7 8
9 10

It now works perfectly !!

Cheers for your help.

Steve.