Silverlight Toolkit error: 'Invalid attribute value controls:LongListSelector for property TargetType'

Question

Whem im add a toolkits objects and run app i always have the same error: Invalid attribute value controls:LongListSelector for property TargetType. [Line: 440 Position: 12], datepicker, timepicker, or switch doesn't matter, whats a problem?

here is datepicker xaml: Controls:DatePicker x:Name="DatePicker" Margin="119,260,0,0"></Controls:DatePicker>

Answer 1

It sounds like you are missing the XML namespace declaration for the Silverlight Toolkit controls. If you are using the controls prefix, then you need the following:

xmlns:controls="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"

NOTE: XML namespace declarations are case sensitive, so you cannot use Controls, just controls

Answer 2

Downloading the last phone toolkit from NuGet will fix the problem.

Answer 3

Maybe you are using the August 2011 Build of the Toolkit together with the old Windows Phone Developer Tools?

The August 2011 Build is dedicated for the 7.1 SDK ("Mango"), so you should either use the 7.1 SDK with the August Build OR use the old SDK with the February 2011 Build.