So I am having an issue using NDSolve and plotting the function. So I have two different NDSolve's in my plotting function (they are technically the same, just have different names but that can be changed back if at all possible because I want them to be the same) but the second one is not working. 

When I remove it from the plot/manipulate command, it works fine and outputs an answer. I just need the expanded form so that I can manipulate the variables (if there is a way around this, that would be great too!)

Here is what I have so far, any help would be appreciated as I have no idea why I am getting this error.

    Manipulate[
     Plot[{
       (Evaluate[
         ReplaceAll[
          Paorta[t],
          NDSolve[
           {Paorta'[t] == 
             1/Caorta ((1/2*k*(1 + Cos[\[Omega] t]) + 10 - Paorta[t])/
                Piecewise[{{Ro, 
                   1/2*k*(1 + Cos[\[Omega] t]) + 10 - Paorta[t] > 0}}, 
                 x*Ro] - Paorta[t]/Rsystemic), Paorta[0] == 90},
           {Paorta[t]},
           {t, 0, 10}
           ]
          ]
         ]), (1/2*k*(1 + Cos[\[Omega] t]) + 
         10), (((1/2*k*(1 + Cos[\[Omega] t]) + 10) - 
          Evaluate[
           ReplaceAll[Pao[t], 
            NDSolve[{Pao'[t] == 
               1/Caorta ((1/2*k*(1 + Cos[\[Omega] t]) + 10 - Pao[t])/
                  Piecewise[{{Ro, 
                     1/2*k*(1 + Cos[\[Omega] t]) + 10 - Pao[t] > 0}}, 
                   x*Ro] - Pao[t]/Rsystemic), Pao[0] == 90}, {Pao[t]}, {t,
               0, 10}
             ]
            ]
           ])/Ro)},
      {t, 0, 10},
      ImageSize -> Large,
      PlotRange -> Full,
      PlotLegends -> {"Aortic Pressure", "Pressure in Left Ventricle", 
        "Flow"}
      ],
     {{Caorta, 1/.48}, 1, 6},
     {{Rsystemic, 3.1}, .1, 6},
     {{x, 8000}, 1, 10000},
     {{\[Omega], 2 \[Pi]}, \[Pi], 3 \[Pi]},
     {{k, 110}, 60, 200},
     {{Ro, .01}, .007, .05}
     ]

Thanks in advance!