ActiveX VT_ERROR, xlsread and Bloomberg API

I am running win7, office 2007, Bloomberg professional and Matlab 2011a.

I have a value in an xlsx sheet equal to "=BDP('SPX Index, 'PX_LAST');

all this does is return a value to this cell, eg "10".

I call the xls sheet through xlsread. When I go to inspect that value I see the content of the cell is "ActiveX VT_ERROR" and not 10.

I don't wish to copy and paste "values" before calling xlsread.m as the process is automated.

How can I import the data into Matlab via the xls sheet? (of course one can use blp.m if not going via xls).

thanks