# Mass\_Level Filter (BoolMask)

**URL:** <https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918>\
**Category:** Revit\
**Created:** [October 6, 2020, 9:35pm UTC](https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918 "2020-10-06T21:35:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jkim](https://avatars.discourse-cdn.com/v4/letter/j/258eb7/32.png) [@jkim](https://forum.dynamobim.com/u/jkim)\
**Post date:** [October 6, 2020, 9:35pm UTC](https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918/1 "2020-10-06T21:35:04Z")

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It seems easy enough, but cannot get this Dynamo to get parameter value (“Level”) to show up correctly… “Level.Name” does not seem to be working…what am I missing?

I am trying to get the names of Level for the Mass placed in Revit Project… and furthermore Filter them by level…

 ![Mass_Level](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/b/c/bce17c117e83962416d1024d946fae96b74f96d0.png) ![Mass_Level_Mask](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/9/8/9842cc3f943cb43732fb739cdcf111173e906457.png)

thanks in advance!

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**Author:** ![blsalvio](https://avatars.discourse-cdn.com/v4/letter/b/ad7895/32.png) [@blsalvio](https://forum.dynamobim.com/u/blsalvio)\
**Post date:** [October 6, 2020, 11:51pm UTC](https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918/2 "2020-10-06T23:51:46Z")

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hi @jkim

please check the first entry of your list of Levels (element 0 of the list) , it is empty that is why you are encountering an error/warning. remove all the `Null` and empty entries and you will be fine.

-biboy

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**Author:** ![Kulkul](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/kulkul/32/49801_2.png) [@Kulkul](https://forum.dynamobim.com/u/Kulkul)\
**Post date:** [October 7, 2020, 2:59am UTC](https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918/3 "2020-10-07T02:59:31Z")

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Hi @jkim

Here is another possible way to filter regardless if the list contains empty or nulls:

 ![image](https://us1.discourse-cdn.com/flex022/uploads/dynamobim/original/3X/1/1/11e8cc7a2b7d8b766ea16061e1ec37eb110b153b.png)

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**Author:** ![jkim](https://avatars.discourse-cdn.com/v4/letter/j/258eb7/32.png) [@jkim](https://forum.dynamobim.com/u/jkim)\
**Post date:** [October 7, 2020, 1:25pm UTC](https://forum.dynamobim.com/t/mass-level-filter-boolmask/55918/4 "2020-10-07T13:25:40Z")

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that worked!

thanks guys!!