Problem based framework for my optimization problem is not working

At first, I was performing an optimization with respect to all elements of 'A' matrix using below command.

[Aopt,fopt]=fminunc(@(A)myObjective(A,N33,p1,v,limit,n),A0,options);

But now I want an extra parameter (x) to be used for optimization also. Hence, I switched to problem based framework implemented using below code segment.

A=optimvar('A',N,3);

x=optimvar('x',1);

fun=fcn2optimexpr(@(A,x)myObjective(A,x,N33,p1,v,limit,n),A,x);

sol0.A=... %initial A0

sol0.x=... %initial x0

sol=solve(optimproblem('Objective',fun),sol0,options);

But, it is not working. I am getting error like this.

Error using optim.internal.problemdef.ProblemImpl/solveImpl

Expected a string scalar or character vector for the parameter name

Error in optim.problemdef.OptimizationProblem/solve

Error in Optimization_FINAL.m (line 145)

sol=solve(optimproblem('Objective',fun),sol0,options);