Prompting user not working ?

[PeterH]

You should count parameters from left, not from right (i.e. "the last").

[CookieMonster]

Parameter two is optional, although not giving a parameter causes it to not work, therefore can I skip parameter two ?

[PeterH]

Parameter two is optional, although not giving a parameter causes it to not work, therefore can I skip parameter two ?

This would mean that parameter 2 is parameter 3

Would you understand what is meant?

[CookieMonster]

Parameter two is optional, although not giving a parameter causes it to not work, therefore can I skip parameter two ?

This would mean that parameter 2 is parameter 3

Would you understand what is meant?

If parameter 2 is optional, then how can you bypass this parameter ?

[RalphM]

Have a look at the last example for confirm() in the help which shows how to skip "unneeded" parameters and adapt it to your needs.
If that's too much to ask then you should probably stay away from scripting.