DIR9001-Q1: PLL cannot lock on input signal

I am inputting TOSLINK to TORX1355(F) to the DIR9001. On occasion during power up the ERROR pin asserts high, AUDIO# asserts low, and no data is transmitted on DOUT. By reading the DIR9001 documentation it would appear the PLL cannot lock on the input signal. 

I say on occasion, but in reality I have only been able to get data on the output a couple times using the same TOSLINK transmitter. 

Do you know why this could be the case? I have attached the relating schematics below.