I have always used [ chart][ /chart]
Just don't use any spaces, then put the url between the ] [
I have not had any problems posting charts unless the website changed it's server protocol, like Bigcharts did with some of the longer term charts.
I don't use stockcharts.com so can't help with that, yahoo, bigcharts work Ok.
Good Luck to All! :^)
PLAN the TRADE and TRADE the PLAN!