Could Someone help me to find out why l.X1 is set to default value(0.0) when the binded source is having a value of 156. Following image may be self explanatory.

Could Someone help me to find out why l.X1 is set to default value(0.0) when the binded source is having a value of 156. Following image may be self explanatory.

Where tag property is assigned in the code, can you please post that code also?
http://forums.silverlight.net/forums/t/66005.aspx
I don't think you can use a DependencyProperty as a BindingSource in SilverLight. See the link above.