Strange HttpGet

Hi all
If I import in xojo some (well working) rb code, I now have a strange problem :
As this line :

SourceSL=SocketMap(pageSL,0)

no more works (sourceSL is empty) I try to use :

SocketMap(pageSL)

with sourceSL=content in PageReceived event
no success (sourceSL still empty)
But if I add MsgBox(SourceSL) all works (sourceSL no more empty)
WHY?