Switch-case error message by matlab

Hey guys, I got this "problem" I made a switch-case thingy and it is working, but matlab shows me these red bars at the right side and tells me "the expression cannot be assigned to multiple values", marking my [P2,FTLE] = FTLE[...] epression.

switch direction
    case 'forward'
        [P2,FTLE] = FTLE_forward(Variables);
    case 'backward'
        [P2,FTLE] = FTLE_backward(Variables);
    case 'both'
        master = 1; %for plot
        direction = Possible_direction{1};
        [P2,FTLE] = FTLE_forward(Variables);
        P2_forward = P2;    
        FTLE_forward = FTLE;

          direction = Possible_direction{2};
          [P2,FTLE] = FTLE_backward(Variables);
          P2_backward = P2;    
          FTLE_backward = FTLE;
      otherwise
              disp('unstruction unclear');
              return;
  end

So what do I have to do or do I even have to change anything at all ? Seems like matlab is not happy that I use these two function in the "both" case again, because if I comment it out, matlab seems to be fine with it.

[Stephen23]

What are FTLE_forward and FTLE_backward: functions or variables?

[H ZETT M]

They are functions.

[Stephen23]

@H ZETT M: okay. Please show us the complete error message. This means all of the red text.

[H ZETT M]

I already found the mistake. in "both" FTLE_forward gets used as a function first, but soon after I create a variable with the same name.