fkWO is a calculation where bump:fkWO = Work Order:pkWO
Will be an unstored unindexed calculation field and thus will not work in this relationship. You'll need to come up with a different way to assign the correct matching value to bump::fkWO so that the field can be an indexed field. You may be able to use an auto-enter calculation or looked up value field option to copy this value over from the related record.
Thanks! auto enter calculation worked.