Check whether current dimension member is Allowed/Denied


I have an AS implementation wherein we restrict access to a Metrics
Dimension based on roles. In my client application, I use [Metrics].&[M0010]
to code that metric in a chart. Now, when a user does not have access to that
metric, I get an error "Cannot find dimension member [Metrics].&[M0010]"
which is an expected behaviour. But, I would like to write an MDX which
checks whether this member is an allowed member. If not, I would like to use
[Metrics].&[M000] which is a dummy metric.

I tried using
iif(isempty([Metrics].&[M0010]),[Metrics].&[M000],[Metrics].&[M0010]) but I
am getting error. I am not able to find any MDX function which checks
whether the current member is allowed or not.

Can someone provide some pointers on getting this to work? Thanks in