Crystal Report Chart Expert showing Count instead of Sum

Sometimes in crystal report while showing a bar chart if we want to show the sum or average of some values other than count, the chart expert may not show you all the summary option like average, sum, mode etc. Though the coding is correct and no error is displayed its just that the chart expert doesn't show the summary option other than count or distinct count. This is because the value for which you want to display average or sum is not of desired data-type, for example, if we want to display marks on the change of roll no. than marks should be of data-type like integer or double rather than choosing the data-type like string. So just check the data-type to get rid of this problem.
Happy coding :)