Has anyone had success in using the zfilter2 opcode?  If I score instrument 1 to play for 10 seconds, while including: a line for zfilter2, the real elapsed time is less than 1 second, and no sound is heard.  This occurs whether or not I actually use the output of zfilter2 as an audio output.  I'm running a Csound 5.09 single-precision floats build on Linux. Thoughts?

-Nik