A problem with diseqc 1.0

#1
Hi, i have a problem with port 3 of diseqc 1.0 switch. It is this:
I'm in port 3. When i go to port 1, always ok. But if select the lnb in ports 2 or 4, coming from port 3, it fails or instead go to port 1.
It is easy to repeat this, tested with two switchs, the same result.
Using win7 32, prof7301, prog 6.60.x
Somebody else noted this?