oDataQuery $filter

Hi,

I have a table, that contains string column "n_Number" with length 25. In that column there are some big numbers.

I need to query numbers like _123%

According two pages:

http://msdn.microsoft.com/en-us/library/gg309461.aspx#BKMK_select

http://msdn.microsoft.com/en-us/library/hh169248%28v=nav.71%29.aspx

I made a query from my table:

?$select=n_Number&$filter=substring(n_Number, 1, 3) eq '123'

But server response: Invalid 'where' condition. An entity member is invoking an invalid property or method.

What am i doing wrong?