SQL Server Linking to Navision C/side

McLean

I have Navision with a C/side db and am building a new application in Sql Server 2000. The idea is to look-up tables in Navision from Sql Server.
When performing a query from within SQL Server the following error message is returned on Code fields.

select No_ from openquery(NAV,'Select No_ FROM Resource')

Server: Msg 7347, Level 16, State 1, Line 2
OLE DB provider 'MSDASQL' returned an unexpected data length for the fixed-length column '[MSDASQL].No_'. The expected data length is 21, while the returned data length is 4.

Any suggestions?
Angus