SQL strul

Har denna kodsnutt som inte funkar i mysql. Nån som kan berätta varför och ändra så den funkar?!

Conn.Execute("Delete From fraga_user Where userid = " & session("sex_id") & " and pollId Not In 
(Select pollId From fraga Where userId = " & session("sex_id") & " Order By pollid desc,userid limit 4)")

Hade förrut så här när det var med access databas:

Conn.Execute("Delete From fraga Where userid = " & session("sex_id") & " and pollId Not In 
(Select Top 4 pollId From fraga Where userId = " & session("sex_id") & " Order By pollid desc,userid)")

Felmess:

Microsoft OLE DB Provider for ODBC Drivers error '80040e09' 
[TCX][MyODBC]You have an error in your SQL syntax near 'Select pollId From fraga Where userId = 9 Order 
By pollid desc,userid limit 4)' at line 1 

/minsida.asp, line 303