Question: dsolve system of equation with IVP

I am trying to solve a system of 5 equations with given initial conditions. It keeps sqwaking and I can't figure out the problem! I have included the commands below:

> sys;
    [ d          23          5         1           1          83        
    [--- AT(t) = --- TB(t) + - MB(t) + -- TD(t) + --- MD(t) - --- AT(t),
    [ dt         450         7         28         100         690       

       d           7          8          d          1          1        
      --- TB(t) = --- AT(t) - -- TB(t), --- TD(t) = -- TB(t) - -- TD(t),
       dt         138         75         dt         18         28       

       d           8                    d          30          1       ]
      --- MB(t) = --- AT(t) - 5 MB(t), --- MD(t) = -- MB(t) - --- MD(t)]
       dt         115                   dt         7          100      ]
> ics := [AT(0) = 690, TB(0) = 450, MB(0) = 7, TD(0) = 700, MD(0) = 3000];
      [AT(0) = 690, TB(0) = 450, MB(0) = 7, TD(0) = 700, MD(0) = 3000]
> ivpsolution := dsolve([sys, ics]);
Error, (in dsolve) invalid arguments; expected an equation, or a set or list of them, received: {[diff(AT(t), t) = (23/450)*TB(t)+(5/7)*MB(t)+(1/28)*TD(t)+(1/100)*MD(t)-(83/690)*AT(t), diff(TB(t), t) = (7/138)*AT(t)-(8/75)*TB(t), diff(TD(t), t) = (1/18)*TB(t)-(1/28)*TD(t), diff(MB(t), t) = (8/115)*AT(t)-5*MB(t), diff(MD(t), t) = (30/7)*MB(t)-(1/100)*MD(t)]}
 

Thanks in advance!