Why am I getting an error when trying to create a test execution id from a test id?

[Tracy Breuklander]

I am trying to add a test execution id from the test id page - under 'test runs' - new test execution and receive the following error:

error associating test executions with test xxx

Test priority with ID undefined does not exist

This test id has been linked to a test plan and user story, so now am trying to create the test execution, under test runs.