I hope this code gives a rough Idea of what I am trying to do, can someone tell me how I've gone about using manipulate in the wrong way and how I might look to restructure this existing code?

What I require it to do is allow me to manipulate the plain with the sliders and display the change graphicaly, I then want the values to directly effect what the sum of the residuals would be if they were to extend down to the manipulated plane, I also want to display that RSS and have it change as the sliders move.

I also cant find a bug that is not allowing the code to find the file regression.xls

The manipulate header

manipulate [

Body of the code

model = z /. Solve[a x + b y + c z + d == 0, z][[1]];
 (-d - a x - b y)/c
   (*get data*)
   data = Import["RegressionExample.xls"][[1]] // Rest;
 (*and header*)
 header = Import["RegressionExample.xls"][[1]] // First
     {"Adverts", "Airplay", "Sales"}
     (*fit the data to the model*)
     fit = NonlinearModelFit[data, model, {a, b, c, d}, {x, y}]
     NonlinearModelFit::fitd : 
       "First argument \!\(data\) in NonlinearModelFit is not a list \
or a rectangular array. \!\(\*ButtonBox[\">>\", \
ButtonStyle->\"Link\", ButtonFrame->None, \
ButtonData:>\"paclet:ref/NonlinearModelFit\", ButtonNote -> \
\"NonlinearModelFit::fitd\"]\)"
        FittedModel[
         0.000927139168578378` (44355.63156634302` + 
            93.71519296640882` x + 3870.819045915761` y)]
        FittedModel[
         0.000927139168578378` (44355.63156634302` + 
            93.71519296640882` x + 3870.819045915761` y)]
        (*sum of squared residuals*)
        sumOfSquaredResiduals = fit["FitResiduals"] // Norm
       693.1292063621133`
       (*range for plotting*)
       {advertsMin, advertsMax} = {Min[#], Max[#]} &@data[[All, 1]]
       {9.1`, 2271.86`}
       {airplayMin, airplayMax} = {Min[#], Max[#]} &@data[[All, 2]]
       {0.`, 63.`}
       (*make the plots separately then combine*)
       (*best fit plane*)
       bestFitPlanePlot = 
        Plot3D[fit[x, y], {x, advertsMin, advertsMax}, {y, airplayMin,
           airplayMax}, PlotStyle -> {Blue, Opacity[.2]}];
 (*original data*)
 dataPlot = 
  ListPointPlot3D[data, PlotStyle -> Directive[Red, PointSize[.015]]];
 (*make the drop lines*)
 lines = Line[{#, {#[[1]], #[[2]], fit[#[[1]], #[[2]]]}}] & /@ data;
 (*plot them*)
 linePlot = Graphics3D[lines];

The Manipulate footer

, {a, -5, 5}, {b, -5, 5}, {c, -5, 5}, {d, -5, 5}]