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Caleb Jenkins is a Silverlight Expert Ninja and a Principal Agile Coach for a fortune 100 global software company, former Microsoft Developer Evangelist, National Speaker for INETA, Microsoft MVP, featured presenter for and Adobe.TV. In the past he's worked as a technical editor for Wrox Publishing and is also a certified Scrum Master. Find out more about Caleb at his blog or follow him on twitter @calebjenkins. Caleb is a DZone MVB and is not an employee of DZone and has posted 16 posts at DZone. You can read more from them at their website. View Full User Profile

An Error You May Run Into When Using Blend For Windows Phone

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I ran in to this recently and couldn’t find anything online about it.

Using MVVM-Light for Windows Phone development and Blend. It works fine in Visual Studio, but every time I open one of my pages in Blend I get this error. 

 Class is already registered. mvvm-light in Blend

Already registered? I’m using MVVM-Light’s integration with a Simple IoC container to manage my dependencies and so it really leaves me wondering what’s going on here. I know that I only registered this class once.. so what gives?

Fortunately for me, Laurent (the creator of MVVM-Light, fellow MVP, and all around Blend Ninja) is active on Twitter and saw my tweet.





hmm.. let’s try that…



and ta-day!


Design time data working in Blend using MVVM-light!.

Special thanks to Laurent for knowing exactly what I needed to do. Thanks my friend!


Published at DZone with permission of Caleb Jenkins, author and DZone MVB. (source)

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