this will often throw as there is no guarantee that the new assembly is Roslyn assembly. For example System.Data could get loaded by Roslyn or user might load his own assembly. Why didn't you use my suggestion to look up by name?
![roslyn-error](https://f.cloud.github.com/assets/1710369/943767/9dbc2df6-025e-11e3-842f-5c7a24a214e4.png)