Incorrect use of dateadd() function

Hi guys,

I have a stored procedure which has a datetime parameter. But when I call it like this:

exec spSomething dateadd(minute, 30, getutcdate())

It complains as "Incorrect syntax near 'minute'.

But when I call it like this:

declare @time datetime
set @time = dateadd(minute, 30, getutcdate())
exec spSomething @time

Everthing is OK. Why? Can you help me on this?

Thank you !

exec spSomething(dateadd(minute, 30, getutcdate()))

?

all sp's expects the parameter while they do not perform any arithmetic on parameter and generate the value for their parameter.