Cascade Checkboxlist loses values on post back

I have four checkboxlist into my web form , they are cascade in nature one selection of first checkboxlist item the second checkboxlist item populates and on selection of second checkboxlist the third checkboxlist item populates and on selection of third checkboxlist item the fourth checkboxlist item populates now if i uncheck the second checkboxlist item then automatically the cascaded items should be disappear and i have done all that the problem with me is that if i select the first checkbox and then second populates and on selection i check the second checkboxlist item the third populates now if i again go to first checkbox list item and check another checkboxlist item then due to post back all the cascaded (below) selection gets cleared due to post back, I have check enableviewstate property of checkboxlist item but it does not work and meanwhile i want to let you know that i do not have code in page load event I just have a checkboxlist (first) on page load all other are populated on selectedindexchanged event of checkboxlist item.


please give me a good and easy solution