php会话不在chrome和firefox中工作但在IE中工作

i know this is a well asked question, but the solution provided doesn't clarify my query... :( php sessions aren't working as expected... for first few tries, the session doesn't get logged.. but after fourth or fifth try, the session is getting logged.. not sure why this doesn't work at first instant... works with IE but not with fireforx and chrome.. i know this is a well asked question, but the s