The flashing LED light indicates the input is not in sync.

Are you clocking an extended system, perhaps including video equipment.  If not, why the Big Ben?

Yes, it seems unnecessary in your system, and only serves to complicate matters!
"Sound on Sound" did a review of such devces last year.  Despite their natural reluctance to discourage advertisers, they could come up with few justifications for external clocking.  The entire article is here@:
http://www.soundonsound.com/sos/jun10/a … clocks.htm

and here is the gist of it:

"The issue here is that it is much easier to design a good clock circuit using a fixed crystal inside the unit than it is to design a circuit which accepts an external clock signal and synchronises to it well. External clocks are likely to acquire some element of jitter (largely because of the inherent effects of clock cabling), and the common slave-locking circuits can introduce further timing variations of their own, both of which can be quite hard (and expensive) to remove. As a result, an A-D will often perform less well when synchronised to an external clock than when it is running on its own internal crystal. The noise floor may rise, and there may be more low-level distortion products and artifacts. That being the case, it makes sense to use a device which can handle external clocks well as the slave, and a device which works poorly on external clocks as the master. In that way, the maximum audio quality can be achieved for all devices.

Why Use A Master Clock?

In most compact project studios, there’s little need for a master clock. The required system clocking can usually be achieved by interconnecting the equipment directly and, as explained above, where there’s only one A-D in the system, it’s generally best to use that as the clock master anyway.