SOLVED - DMX Shield only works with Startaddress 1 ?

I have the CTC-DRA-10-R2 mounted on a Arduino UNO and i use the Conceptinetics.h library

As long as the Startadress is set to "1" everything works fine, but as soon, as i change
the startadress nothing is happening on any chanel .

Can someone help ?

EDIT: Thanks so far, but i found the solution. The documentation says : "...is relative to the startaddress" so it must be "dmx_slave.getChannelValue (1);"
and NOT "dmx_slave.getChannelValue (startadress+1);"