Problem with Graphs in Bugzilla 2.17.4

[prasad]

Hi ,

I am having a problem with my instance of Bugzilla.

1. On the Generate Report page(by following the link  of Graphical 
Reports)  when i  select  the  horizontal aswell as  vertical axis  and 
select  Bar or pie  then the graphs are not displayed.

2. But in case of Line the Line graph is displayed.

3. But on following either the Bar or pie graph  links which are on the 
page displaying  Line
 graph the appropriate Bar or Pie graphs are displayed properly.

4. one thing i have got and not understood  is that the parameters 
passed to the CGI programs for displaying Bar Graphs in both cases  are 
different.

please give me a solution to this problem..........................