Need to know the max and min delay for a group of nets

Hi everyone,

 I need to know the max and min delay for a group of nets, and I've been trying to do it with the report_timing command.

The outcome has been that it keeps telling me that: 

                      No unconstrained timing paths with given description found.
                      Paths may be constrained or may not exist. 

I've tried:

 report_timing -from [get_ports *adc*] -to [get_pins core/sl_*/bl_*/*lt*/E]

report_timing -path_exceptions all -from [get_ports *adc*]  -unconstrained

report_timing -to [get_pins core/sl_*/bl_*/*lt*/E]

... and 100 more combinations of the like.

Anyone can give me an idea why ik keeps failling me?  

Thanks for any help/idea,

Ivan