Problem refreshing canvas when multiple windows and canvasses.

Question

Ok I Have a form that has 2 windows and 2 canvases.
They both get populated on When new Forms instance trigger with a parameter i pass in from teh previous form.
On entering the form if the parameter is set (passed in by the form before) it should query the blocks on canvas 1 and display the second canvas/window via a seperate package of "canvas.open" which is a package to open and populate the second canvas which is a tree.
If this code is fired on a key next item or a button press its fine. but not where it is on when new form instance trigger. The canvas.open simply stops on a synchronize early on. If i remove a sync then the second canvas never appears.
You can see a commented out pause. If this is included then it all works fine. If i use a synchronize instead of the pause it doesnt even reach the canvas.open (i used messages on status to work this out)
So my question is how can i get a synchronize to work as i assume this is whats missing?
Any help much appreciated, Im sorry if i have not explained very well.
IF :PARAMETER.I IS NOT NULL THEN                    
               Go_Block('B1');               
               Execute_Query(no_validate);
               Go_Block('B2');
               Execute_Query(no_validate);
--PAUSE;
               canvas.Open(:PARAMETER.I);                    
END IF;          

Answer 1

What happens if you do a
IF :PARAMETER.I IS NOT NULL THEN                    
               Go_Block('B1');               
               Execute_Query(no_validate);
SYNCHRONIZE;
               Go_Block('B2');
               Execute_Query(no_validate);
SYNCHRONIZE;
               canvas.Open(:PARAMETER.I);                    
END IF;