Tray-Control Duplex

[max server]

Hi,
I have a problem

I want to print duplex and provides pages of an other tray printing (also duplex)!

lp -d myprinter -o Duplex=DuplexNoTumble -o PageSize=A4 -o InputSlot=Manual -o 3:InputSlot=Tray1 -o 4:InputSlot=Tray1 /mydoc.pdf

The document has 6 pages!
Page 1 and 2 also 5 and 6 will be correctly printed (duplex)
Page 3 and 4 be printed simplex !
The same even if „Tray1“ and „Manual“ swap!
So both trays can duplex print!
What am I doing wrong?

Thanks