Hi Madhu,
There could be a number of reasons for set()/get() not working, but they boil down to:
(1) make sure the set() happens before the get().
(2) make sure the set() and get() have matching lookup strings
(read the Cookbook page on this topic at UVM Configuration Database | Verification Academy)
(3) make sure the same type (including any parameterization) on both ends
If you still are having unexplained problems in the set / get config there is a debug tool built into UVM you can use, and also debug tools in your simulator (e.g. refer to the Questa UVM debug in your documentation)
To debug set/get, add the following code prior to your first ‘set()’ call:
uvm_config_db_options::turn_on_tracing();
You mentioned access to the config object from your sequence - read also the Cookbook page at Config/ConfiguringSequences | Verification Academy for some useful techniques.