overwrite outputs in file geodatabase arcgis 10.1

hello everyone
well
i am using moderbuilder to automate some geoprocessing work. i have used arcgis tool in model builder then save the model to run, whenever it is needed. problem is
when i run the model it give me massage the output already exists. i want to overwrite the output features that are stored on database. i have enable the option in geoprocessing "overwrite the geoprecessing results" but it does not work. please let me know how i can do this that everytime when i run the model it overwrite the previous files in the geodatabase. overwriting is important so i am not ok with alternatives.

thanks alot