'Telerik.Web.UI.RadListBox' is null or not an object

[Juan Carlos Juarez]

Hi, I get the error 'Telerik.Web.UI.RadListBox' is null or not an object when I have a RadListbox present on my .ascx control firstable with visible as false, but when I try to show this control, this error occurs. It is not exclusive for this control on my sharepoint application, I have the same error with others Telerik controls that have the same behavior ( starting are hide, and then I need to show them).

I followed this post, but I'm sure that all the entries and configurations are done on my application config. The version of telerik that I'm using is the 2010.3.1109.35

Thanks.

[Kalina]

Hi Juan Carlos Juarez,

Let me suggest you add the script references for RadListBox control and the other controls that you use manually through the ScriptManager  - as described in this help article.
I hope this helps.

All the best,
Kalina
the Telerik team