I have a Layla 24 on a computer running GigaStudio and an M-Audio Firewire 410 on my other machine. I connected them with optical SPDIF. The sync source on the Firewire 410 is set to "external optical". Under "digital" on the Layla 24 I have selected "SPDIF Optical". The SPDIF light on the Firewire 410 is on indicating it is receiving a signal, but the Firewire is not getting any actual sound from the Layla (Gigastudio). help!!