Import error - java.lang.nullpointer error when using Saleforce importer with salesforce sandbox

[lightsailpro]

I am trying to import some Salesforce objects from Salesforce Sandbox environment. I am was to connect to the sandbox, retrieve the objects and select the object, but the end, I got "import error" with detail error (java.lang.nullpointer). For the Sandbox Salesforce url, I used the following: https://test.salesforce.com/services/Soap/u/31.0. Is this the right url and right version of the soap endpoint for Sandbox? The importer works fine for the Sandbox production environment. Thanks in advance.

[rareddy]

I use https://www.salesforce.com/services/Soap/u/22.0 for testing with my account, sandbox should work same. Note that Teiid version is at 22. You can try https://test.salesforce.com/services/Soap/u/22.0

Also we would need more information than "import error", post the whole stacktrace to see where the error happening?

Ramesh..

[lightsailpro]

Changed to 22. The import error went away. But was not able to query any tables from the Sandbox, The query just hang in SQL workbench.