populating incorrect namespace is Xpath assertion

I have a REST URI , something like

https://testserver.mycompanydomain.com/v1/employee/

its used to pull employee information , by passing employee id

https://testserver.mycompanydomain.com/ ... yee/123456

When I trying to create Xpath Assersion, its declaring namespace like this

declare namespace ns1='https://testserver.mycompanydomain.com/v1/employee/345678';
//ns1:Response[1]/ns1:employeeID[1]

where 345678 is the employee id passed in the most recent request. So the name space become dynamic, and the Xpath assertion when trying to use this assertion for a different employee id

instead, name space should be declared as (without the hardcoded employee id value)

declare namespace ns1='https://testserver.mycompanydomain.com/v1/employee/';
//ns1:Response[1]/ns1:employeeID[1]

Please advise on what could be wrong and possible solutions.

Thank you