Question: trying to find a minimum of this expression..but

hi, i am trying to find a minimal value for an expression

orginally the expression comprised of two variables t and a

after taking a definite integral from t=0..t=1, the expression should only contain a

and using the commands, i found:

>
> e := Int(k^2, t = 0 .. 1);
print(`output redirected...`); # input placeholder
   /1                                               
  |   /        //10      \ /3   3       /         2\\
  |   |2985984 ||-- - 8 t| |- - - t + a \2 t - 3 t /|
  |   \        \\3       / \4   2                   /
 /0                                                 

      /  3              \ /2   10        2\\  \///                    
    - |- - + a (2 - 6 t)| |- + -- t - 4 t ||^2| \\145 + 316 t + 432 a t
      \  2              / \3   3          //  /                       

              2         2           3        2  2         2  3         2  4
    - 1512 a t  + 1156 t  + 1296 a t  + 576 a  t  - 1728 a  t  + 1296 a  t

            3         4\  \  
    - 3840 t  + 2304 t /^3/ dt
> with(Optimization);
print(`output redirected...`); # input placeholder
  [ImportMPS, Interactive, LPSolve, LSSolve, Maximize, Minimize, NLPSolve,

    QPSolve]
> Minimize(e);
%;
Error, (in Optimization:-NLPSolve) summation variable previously assigned, second argument evaluates to 1. = RootOf(145+3600.*_Z^4-4272.*_Z^3+220.*_Z^2+748.*_Z)
 

i am really new to maple and am stuck in finding the minimal. is there way to do this?