Solve function with integration giving error. Please suggest the solution

Please suggest the solution for the encoutering problem below:

   I plotted the function by varying V as:

for V=0:1:10 plot(V,integral(@(x) x.^2.* exp(-x-1./(x+V)),1,inf )); hold on end

From this I can see that it is giving positive values. So, if I want get value of V for given integral value as:

solve(integral(@(x) x.^2.* exp(-x-1./(x+V)),1,inf ))==1.4,V)

From above 'for' loop the value should come as V=1. But it is giving the error as:

Undefined function or variable 'V'.

Error in @(x)x.^2.*exp(-x-1./(x+V))

Error in integralCalc/iterateScalarValued (line 314) fx = FUN(t);

Error in integralCalc/vadapt (line 133) [q,errbnd] = iterateScalarValued(u,tinterval,pathlen);