can't find 'clk' pin using get_pins in timequest timing analyzer

The experience I had was that, even if I put attributes like 'preserve' or 'noprune' on the register, sure the register would not get optimized away. however, you could still not find the 'clk' pin in the timing analyzer. I think this is a bug in the tools.

Response from Altera to one of my service requests:

'Thank you for letting me know. The software engineer has confirmed that the register with no fan-out is eliminated from the timing netlist. This is why you aren't able to locate the register and the input/output pins of the reigsters. He said this is by design, so in order to work around this, you would need to have the register's output driving something (as you are doing now).'