The following code, in a startup .prg, works fine (and runs the form):

CurDataSource="r:\data\my_data.dbc"
Open database (CurDataSource) shared
Set database to (CurDataSource)
Do Form Test_Form


However, when I keep the "dbc" extension off the "CurDataSource" variable, I get an "Error instantiating cursor object" error when the form loads. Is there any reason for needing the "dbc" extension?