string on GUI.Button not showned

I am sure that inventoryItem.Name contains "Wood" cause i see it when i add a breakpoint. Still i get nothing in the game. Just empty buttons.

void DrawInventoryContent (int id)
    {
            var buttonIndex = 0;
            var x = 0;
            var y = 0;

            foreach (var item in inventoryItems) {
                    //create position rectangel for button
                    var startMargin = buttonMargin;
                    var leftStartPosition = startMargin + buttonMargin * x + buttonWidth * x; 
                    var topStartPosition = startMargin + buttonMargin * y + buttonHeight * y;
                    var buttonRectangel = new Rect (leftStartPosition, topStartPosition, buttonWidth, buttonHeight);

                    //Get inventoryiten by index
                    var inventoryItem = inventoryItems [buttonIndex];
                    var name = inventoryItem.Name;

                    //Create and place buttin
                    GUI.Button (buttonRectangel, name);

                    // check if this button is at end of row and change to next row
                    if (x == buttonsPerRow - 1) {
                            x = 0;
                            y++;    
                    } else {
                            x++;
                    }
                    //go to next item 
                    buttonIndex ++;

            }
    }