How do you format a connection string path when the data is in a folder under the app_data folder?

I have

<add name="vfpRTP2" connectionString="Provider=VFPOLEDB.1;Data Source=|DataDirectory|2040sharedfiles\2040rtp.dbc" providerName="System.Data.OleDb"/>

Which works when I run the form but fails when I configure the datasource.

The problem seems to be with the folder delimiters. I have tried several combinations but can't find the right one.

Thanks