Alleged incident occurred while EE was attempting to change a drill pot on roof bolting machine. EE lifted drill pot to knee level when he felt a pain in his lower back. EE did not report incident or miss work until 8/18/2008 and also missed work on 8/19 and 8/20. EE did RTW on 8/21/2008. The person filing this report was made aware of the incident on 8/28/2008.