Can't solve ODE with pchip and ppval

Hi, I'm getting a error I can't understand and I would love if someone could clarify for me why the following doesn't work: I have two ode's, one with and one without noise. The one with works, but the one without doesn't. The one without looks like this:

function [dFTdt] = SVP(t,x,p,SVP)
alpha = p(1);
beta = p(2);
ki=p(3);

FT=x(1);
dFTdt = zeros(1,1);
dFTdt(1)=beta - ppval(SVP,t) * ki - FT * alpha;
end

and the one with like this:

function [dFTdt] = SVPnoise(t,x,p,SVP)
alpha = p(1);
beta = p(2);
ki=p(3);

FT=x(1);
dFTdt = zeros(1,1);
dFTdt(1)=beta - ppval(SVP,t) * ki - FT * alpha + normrnd(0,0.5);
end

I can solve the one with noise in the following way:

[~,yx] = ode45(@(t,x) SVPnoise(t,x,BestLSQ12,SVP12),tData,FT(1,1))

where

BestLSQ12 = [327.1456  591.7595  471.9959]; SVP(:,1) = 0.5000 0.8000 0.3000 0.7500 0.5000 0.2500 0.2300 0.4000 0.2400 0.2000 0.7000 0.3500 0.3500 1.0100]; tData = 1.0000 1.3300 1.6600 2.0000 2.3300 2.6600 3.0000 3.3300 3.6600 4.0000 4.3300 4.6600 5.0000 5.3300]; SVP12 = pchip(tData,SVP(:,1)); FT(1,1) = 0.1000; 

I solve the one without noise in the following way:

[~,yx] = ode45(@(t,x) SVP(t,x,BestLSQ12,SVP12),tData,FT(1,1))

and then I get the following error:

Function 'subsindex' is not defined for values of class 'struct'.

Error in @(t,x)SVP(t,x,BestLSQ22,SVP12)

Error in odearguments (line 87)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

Error in ode45 (line 115)
    odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

I'm still a MATLAB novice, so I have no idea why this appears. I would love to know for future progress. If anyone care to write a short line about it---I would be very grateful. //Best regards