# Item Selector Error

**URL:** <https://discourse.mcneel.com/t/item-selector-error/172635>\
**Category:** Human\
**Tags:** windows\
**Created:** [January 4, 2024, 9:25am UTC](https://discourse.mcneel.com/t/item-selector-error/172635 "2024-01-04T09:25:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Vagdalt\_Brendon\_Axel](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/vagdalt_brendon_axel/32/533035_2.png) [@Vagdalt\_Brendon\_Axel](https://discourse.mcneel.com/u/Vagdalt_Brendon_Axel)\
**Post date:** [January 4, 2024, 9:25am UTC](https://discourse.mcneel.com/t/item-selector-error/172635/1 "2024-01-04T09:25:57Z")

</div>

Hello, I’m a new user of Rhino. I want to simulate a natural ventilation on an office building. At the first stages, I created the building model divided into spaces with closed polysurfcaes.  
But when i want to use inside grashopper the HB Instersect solids output connect to an item selector, and than a HB room from Solid, than i could make different level with different space data, the program show an error.

Thank you in advice for your help.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/8/7/c/87c50ab2cc4bc27bfc72207b2d6c058be5028615.png)