(See Attach) EE states he was lifting a railcar shaker and he thinks the injury could have possibly occ. during perf. of that task. EE did not report this to co. officials until he returned from vacation, approx. 1 week after possible occur.It is still unclear if this occurred during perf. of the EE's duties while on co. property. No Witness, W.C. will issue letter of denial.