In reply to shekher201778:
You should read the UVM Cookbook article on Sequence Arbitration. The default arbitration method is UVM_SEQ_ARB_FIFO, which will select the sequences in order of execution, ignoring any priority. Since you started the sequences with a fork statement, the order of execution is indeterminate.
If you want the sequence priority to be taken into account, you need to specify a different arbitration method.