Joining two databases for Gridview column name error

I am trying to join together two databases based on a common ID, "PropertyID"
However I keep running into invalid column name errors.
I have played about but keep running into these errors. The current errors are:

Invalid column name 'PID'. Invalid column name 'TPD.PropertyID'. Ambiguous column name 'PropertyID'. with code. 
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:GWmyPemcoSQL %>" SelectCommand="SELECT PropertyID as PID,PropertyName, RegionID from TbPropertyDetails TPD JOIN TbPropertyDetailsSafeguarding SAFE ON SAFE.PropertyID = TPD.PropertyID where ([RegionID] <> '0') and ([PropertyID] LIKE '%' + @PropertyID + '%' ) order by TPD.PropertyID asc;"> <SelectParameters> <asp:SessionParameter DefaultValue="xyz789" Na ...