Encounter CTE is not tracing the clock

I am getting the following ERROR, WARNING while doing the createClockTreeSpec

**WARN: (ENCCK-3179):Clock ldpc_core_clk does not have any sync pin based on clock tree spec file and CTS tracing algorithm. Please check your spec file to see if AutoCTSRootPin is correctly set, and, if any LeafPin/ThroughPin is left undefined for the clock tree.Cannot trace clock ldpc_core_clk, remove from CTS list!

When I am looking into the .lib of u_ecc macro , I find clock true on the pin ldpc_core_clock. Which is the sink point for the clock  ldpc _core_clock at the top level. See the following report.

encounter 47> all_registers -clock ldpc_core_clk                                      

u_ecc

0x2dcd3

Will you please tell me why encounter is not able to trace the ldpc_core_clk.

Thanks

Ashok