I would assume that whatever user your script is running under does not see the DSN OurDatabase. For an administrative approach, I like setting up DSNs using odbcad32.exe, that way, the DSN together with the credentials is available from about any ODBC-enabled application.

For the same reason, it might be inadvisable to store the DSN. Then, I would go for a DSNless ODBC approach, using information from http://www.connectionstrings.com/ on how to connect to whatever database there is.