No Result shown when Contacts are added into Activity Report

Hi,

Users want to see list of Activities(fields like Status, Type, Subject, Priority) created by their own in a Report form. They also want to see Account name & Primary Contact's name of those Activities.

When Account name and Contact's First name and Last Name is pulled along with other activity columns and report is displayed on a global applet on My Homepage, then the report shows 'No Result' when logged in as a user. Administrator is able to see the result for the same report. 

When Contact's columns are removed then the report shows correct details and also displays Account for all the users including Administrator.