Hi,
thanks for the answer..
here is the constraint (BTW, i generated it through the create clock option in the Time Quest Analyzer GUI):
# **************************************************************
# Time Information
# **************************************************************
set_time_format -unit ns -decimal_places 3
# **************************************************************
# Create Clock
# **************************************************************
create_clock -name {CLOCK_50} -period 10.000 -waveform { 0.000 5.000 } [get_ports {CLOCK_50}]
# **************************************************************
# Create Generated Clock
# ********