please help , vb script , multiple tabs ,

i use vbscript to autologin to specific page , very well , but always when i open another tab i can't control forms in that tab

dunno why ? !!

like for example :
ie.navigate2 "http:/myothertab/", 2048

ie.AddressBar = 0
    ie.Visible = 1
    ie.ToolBar = 0
    ie.StatusBar = 1
IE.Visible = true
ie.Document.All("myvalue").value = "username"

always get an error 

is there any thing else i should add to control the fields in the other tabs ?

thanks in advance