Detect Value Entered in Filter

Hi,

I am passing Filter Value from Dashboard to WebI Report.

this Value may be multiple or Single or "ALL"

As ALL is not a parameter value for Filter

I am passing ALL as NULL(BLANK) thus Report Filter will take all possible Values

Now in report If filter received NULL i want to simply Print "ALL"

else Value.

I tried Userresponce()

Reportfilter()

IsPromptAnswered()

but some how not working.

Can any one Help?

Thanks in Advance.