silverlight bing mapcontrol setview inconsistent results

Question

silverlight 5 navigation app, creating a location rect from a list of locations as parameter for set view, leave the page, return, pass same list of locations as a location rect 

 the resulting viewport is not the same generally, zoom level is minus one.  

Have tried, storing the resulting center and zoom level after passing in the rectangle, and recalling setview with center and zoom, its not working, more or less the exact same problem, have only left to try storing the resulting bounding rectangle after the first call to set view and re - using it,

but shouldnt have to do this.  Of course totally avoiding databind zoom level and center.

I realize there is alot of calculation involved.  Are there some setting I should have, does the map need to be in a certain ratio of height and width?  Do I need to set a height and width? 

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Athena Capsis

Answer 1

was able to solve the problem of returning to the same view... calculated by setview
using  the view_changeEnd event to capture the center and zoom level arrived at by prior call to setview with my location list generated location rect. 

Having captured the center and zoom level, was able to achieve the same map envelope by setting the center and then the zoom level ( rather than using set view again)

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Athena Capsis