Thanks raphael1, for your reply. but i solved this problem. actually this problem triggered when i included two files which has the
same class name.
for example ,
first.php contains a class called " transaction" and second.php also contains "transaction" class but with different functions in it.
when we include both these files(first.php,second.php) it'll trigger the "cannot redclare class" , that is why i asked you how to
remove one file that has the same class declaration. i just renamed one class now its works well.