This just started happening at a client.  They have a detail line on a sales order that contains a kit with quantity ordered = 1.  The kit contains (among other things an item that's serialized).  They enter the quantity shipped of 1 for the kit and open the component screen which shows quantity shipped of 1 for the serialized item. They open the serial number assignment screen and the screen does NOT allow the selection of the serial number.  The screen is basically greyed out so all you can do is close it.

They have been shipping this item over the past year successfully and I checked that the serial #s were available at the location and not allocated. 

Has anyone seen this before?  What would cause the screen to not allow the serial # selection?

Any and all advice greatly appreciated,

Dana