Harley's parent club Notts County have not yet been back to the Millers to confirm if he can play in Saturdays cup game at Barrow.
The same fate awaits Guy Branston who is on loan from Bradford, and with boss Andy Scott thin at the back due to continuing injuries he's hoping the duo get the nod to feature.
Scott commented to the clubs official website; "We have agreed something with Jon and Notts County which will take us through to January. However we are still waiting to find out about his FA Cup availability."