Plot with three functions ana three parameters

i think my code doesn t have any problem but the program shows me this error and i comfused!/* Plot::argr: Plot called with 1 argument; 2 arguments are expected.*/

 a = 1; l = 2;     w1[x_, c_, theta1_] := x^c + theta1;     f[x_] := ( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a];     mesi = Integrate[x*f[x], {x, 0, Infinity}];     mesi1 = Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0, Infinity}];     fw1[x_, c_, theta1_] := ((x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]))/(Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0, Infinity}]);     DH1[x_, c_,theta1_] := ((Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0,Infinity}])/((Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0, Infinity}]) +theta1))*(((x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/ Gamma[a]))/(Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0, Infinity}])) + (theta1/ (Integrate[(x^c + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]), {x, 0, Infinity}]) + theta1)*(( l^a*x^(a - 1)*Exp[-l*x])/Gamma[a]);  Manipulate[Plot[DH1[x, c, theta1]], {x, 0, 100}, , {c, 0, 10}, {theta1, 0, 10}]  /*my plot doesnt run ? i want to run this function with mean mesi */