sorting bug in streaming date

Hi you have made a grate work here, but I thing there is a bug in sorting when. I use your grid to make a streaming data "data in the grid changed every n seconds ". when i sort any column it is sorted correctly, but when data is changed in the cell and then try to sort the same column again I got a wrong sorting for EX : first column contains these values (100,102 , 105 , 108) in it's initial state and this sorted correctly , but when these date is changed (104,102,109,108) and try to sort table again I still get the old sorting.

waitin your replay , thanks for your grate work