Sstrhsrtj

The equation is attached here.

begin{multline}label{eq6}

MIleft( {E,{E^t},E_k^n,E_l^m} right) = 

sumlimits_i {sumlimits_j {pleft( {{E_i=0},E_j^t=0,E_k^n=0,E_l^m=0} right)

{{log }_2}left( {frac{{pleft( {{E_i=0},E_j^t=0,E_k^n=0,E_l^m=0} right)}}

{{pleft( {{E_i=0}} right)pleft( {E_j^t=0} right)pleft( {E_k^n=0} right)

pleft( {E_l^m=0} right)}}} right)} }+{pleft( {{E_i} = 0,E_j^t = 0,E_k^n = 0,E_l^m = 1} right)

{{log }_2}left( {frac{{pleft( {{E_i} = 0,E_j^t = 0,E_k^n = 0,E_l^m = 1} right)}}

{{pleft( {{E_i} = 0} right)pleft( {E_j^t = 0} right)

  pleft( {E_k^n = 0} right)pleft( {E_l^m = 1} right)}}} right)}

end{multline}

With multline, long equations do not break magically into lines: you have to specify which line breaks you want. You can add the fleqn environment, from nccmath to have a nice layout.

Also, you don't need all those pairs braces, so I removed them to have a more readable coe.

documentclass{ieeetran}

usepackage{mathtools, nccmath}

usepackage{lipsum}



begin{document}

lipsum[2]



begin{fleqn}

begin{multline}label{eq6}

MIbigl(E,{E^t},E_k^n,E_l^m bigr) =\

sum_i sum_j pbigl(E_i=0 ,E_j^t=0,E_k^n=0,E_l^m=0bigr)times \[-1ex]

log _2 mathrlap{Biggl(frac{pleft(E_i=0, E_j^t=0, E_k^n=0, E_l^m=0right)}{pleft(E_i=0 right)pleft(E_j^t=0right)pleft(E_k^n=0right)pleft( E_l^m=0 right)}Biggr)} \

{}+pleft(E_i = 0, E_j^t = 0, E_k^n = 0,E_l^m = 1right)times{} \

log_2left(frac{pleft(E_i = 0, E_j^t = 0, E_k^n = 0,E_l^m = 1 right)}{pleft(E_i = 0 right)pleft(E_j^t = 0right) pleft(E_k^n = 0right) pleft( E_l^m = 1 right)}right)

end{multline}

end{fleqn}



end{document} 

You may want something like this:

documentclass{IEEEtran}

usepackage{newtxtext,newtxmath}

usepackage{amsmath}

usepackage[nopar]{lipsum}% just for mock text



begin{document}



lipsum[3]

begin{equation}label{eq6}

begin{aligned}

&MI( {E,{E^t},E_k^n,E_l^m} ) = {}\

&begin{aligned}

sum_i sum_j

  &p( E_i=0,E_j^t=0,E_k^n=0,E_l^m=0) \

  &cdotlog_2biggl(frac{p( E_i=0,E_j^t=0,E_k^n=0,E_l^m=0 )}

                          {p(E_i=0)p(E_j^t=0)p(E_k^n=0)p(E_l^m=0)}

              biggr) \

  &+p(E_i = 0,E_j^t = 0,E_k^n = 0,E_l^m = 1)\

  &cdotlog_2biggl(frac{p(E_i=0,E_j^t=0,E_k^n=0,E_l^m=1)}

                         {p(E_i=0)p(E_j^t=0)p(E_k^n=0)p(E_l^m=1)}

              biggr)

end{aligned}

end{aligned}

end{equation}

lipsum[4]



end{document}

I loaded the newtx... packages so to have math in Times font.

I also removed all your left and right instructions, most of which simply do damage to spacing. Also most of the braces were either useless or even harmful. For instance, you should never type {log}_2, but only log_2.