Question: What is wrong with the command line: sum(n^4,n)

Dear Maple Team,

     I found a very strange thing in my Maple 14: When I typed the two command line as follows:sum(n^4, n); expand(sum(i^4, i = 1 .. n)), the results are not the same. Now I copy them here.

                   1  5   1  4   1  3   1  
                   - n  - - n  + - n  - -- n
                   5      2      3      30 
                   1  5   1  4   1  3   1  
                   - n  + - n  + - n  - -- n
                   5      2      3      30 

As you can see, the coefficients of the second term are very different.  I know the second result is right, and the first is wrong.　How could this happen? What is wrong with the first command line?

      Thanks a lot

Yuanhong Zhi

Yunnan University