My sincere apologies! I looked in my book, and saw sometimes I was right, sometimes I wasn't.
Serbian delegation, on head with N. Pashic visited Russia (Odessa, where Serbia got consulate), In late April of 1916.
But, Alexander's attempt happened earlier in February of 1914 (before visiting Romania), during Christening of son of Helen of Serbia (sister of Alexander) and GD Ioann Kontantinovich, N. Pashic and Prince-regent Alexander arrived to Russia.
N.PAshic:
''If it would be fate for us to have daughter of Russian Emperor for Queen, she would be gladly accepted by Serbian people, and if God would allow, she might be become Tsarina....''
Nicholas II:
''For Serbia, we will do everything, greet the King, and say to him so. ''
Nicholas' diary entry from January 12th mentions Christening of Prince Vsevolod Ivanovich. Probably Nicholas' didn't mention this meet. I guess because of many people there, he mentioned only important lines during that day. So, probably meet was in January, not in February, but have to check Nicholas' February entries too. (?).