Strange NULL value

Hi all

Hope you can help. It says:

[Destino Cust Ledger Entry [27]] Error: SSIS Error Code DTS_E_OLEDBERROR.  An OLE DB error has occurred. Error code: 0x80004005.
An OLE DB record is available.  Source: "Microsoft OLE DB Provider for SQL Server"  Hresult: 0x80004005  Description: "The statement has been terminated.".
An OLE DB record is available.  Source: "Microsoft OLE DB Provider for SQL Server"  Hresult: 0x80004005  Description: "Cannot insert the value NULL into column 'CompanyID', table 'BI4TEST.fact.Cust_ Ledger Entry'; column does not allow nulls. INSERT fails.".

the data is retrieved from a stored. proc. and then dumped into a destination. I run the proc. in the query analyzer and I dont see any NULL in the CompanyID column.

Tried to (it should never come null but):

    if (@CompanyID is null) or (@CompanyID=null) or (@CompanyID='')
                    set @CompanyID='N/A'

but same result.

I dont know whats going on.

thanks!