Dialplan from an old A@H modded by ????

exten => s-BUSY,1,AGI(debordement.php|${ARG2})
exten => s-BUSY,2,NoOp("poste de debordement ${DEBORDEMENT}")
exten => s-BUSY,3,GotoIf($[${DEBORDEMENT} = vm]?s-VM,1)
exten => s-BUSY,4,Dial(SIP/${DEBORDEMENT})

The same for s-NOANSWER

Here are the logs:
    -- AGI Script debordement.php completed, returning 0
    -- Executing NoOp("SIP/altitude.fr-b7d07120", ""poste de debordement vm"") in new stack
    -- Executing GotoIf("SIP/altitude.fr-b7d07120", "0?s-VM|1") in new stack
    -- Executing Dial("SIP/altitude.fr-b7d07120", "SIP/vm") in new stack

GotoIf always returns 0.

I also tried:
exten => s-BUSY,3,GotoIf($[${DEBORDEMENT} = "vm"]?s-VM,1)
exten => s-BUSY,3,GotoIf($["${DEBORDEMENT}" = "vm"]?s-VM,1)

Same result.