Error using SumOperator with Optimization Variables

I have an Optimization Problem where I created the optim. variable x and the optim. problem linoptim.

Now I am trying to define my constraints and I keep getting an Error

nTasks = 3;

nRess = 2;

maxPT = 50;

x = optimvar('x',nTasks,nRess,maxPT,'Type', 'integer','LowerBound',0,'UpperBound',1);

Constraint1 = sum(x,[2 3]) == ones(nTasks, 1);

"Error in using optim.internal.problemdef.SumOperator

Dimension argument must be a positive integer scalar within indexing range.

If I write the same command and instead of x am using a matrix it works just fine:

sum(rand ([3 2 50]), [2 3])

Answer 1

[Torsten]

nTasks = 3;
nRess = 2;
maxPT = 50;
x = optimvar('x',nTasks,nRess,maxPT,'Type', 'integer','LowerBound',0,'UpperBound',1);
Constraint1 = sum(sum(x,2),3) == ones(nTasks,1);

[Andra Vartolomei]

Thank you! :)

[Torsten]

Little deficits of problem-based programming ...