The tab should be enabled if the Multilevel Repair check box is selected for the shop order, and you have reserved a serial or lot batch number for the part to repair and it has an as-build structure. 

Thanks for the Reply…
as you mentioned in shop order Multilevel Repair check box is enabled, for As built structure kindly let me know where we have to define this.

As-built structure means you must have earlier manufactured the part in IFS using a normal shop order so that a record exist in the As-Built Structure window. The as-built structure contains the serial/lot/batch relationships between the product and the components used.

Thanks a lot !

It worked Bjorn

@Björn Hultgren

I have a problem for our repair shop order that Multilevel Repair Structure tab is not enabled. below shop order is created in another site 1, which is the sales site, customer returned the broken product back to site 1 and site 1 is responsbile for disassemble the broken component. the As-Built Structure is created in site 101, the manufacturing site.

@ronhu The as-built must exist on the same site as you create the multilevel repair shop order. Please consider requesting this to be enhanced to a future release from the idea section of the community.

@Björn Hultgren Thank you.