get_service_paths jtag_debug returns null

Hello,

I am using a DE0-Nano FPGA and I got the follow error every time that in system-console I write the following tcl script command:

set jtag_path [lindex [get_service_paths jtag_debug] 0];

jtag_path does not getting any value and fails in successive steps (ie. opening the service etc..)

I did try the same command with different numbers ie.

set jtag_master [lindex [get_service_paths master] 1];

set jtag_master [lindex [get_service_paths master] 2]; etc... without luck

Appreciate your inputs,

Thanks

barn[/B][/B]