Hide Button Functionality not working properly

Hi All,

I have implemented a Client Side Extension to hide 'Add Attachment' button at various places for Service Request Entity in CRMOD.Please find below the code I have written in Client side Extension:

oraclecrmod.onReady(function()
{
oraclecrmod.getButton("BTN_TB_ServiceRequestFAChildList_AddA").hide();
});
oraclecrmod.onReady(function()
{
oraclecrmod.getButton("BTN_TB_ActionFAChildList_AddA").hide();
});
oraclecrmod.onReady(function()
{
oraclecrmod.getButton("BTN_TB_ActivityListAttachment_AddA").hide();
});

ISSUE: The hide button fuctionality is not working properly it works on some machines while doesnt work on some machiens. The login credetials used for loggin into different machines are same but the buttons are still visible when logged in from some machines while working fine when logged in from few machines. Is there anything which needs to be done locally on sepcific machines, i am unable to tarce the reason for this behaviour. Could anyone please help me to resolve this.