Mozzarella - Melting Question For Use In Cooking

[Melisandre]

Hello all!

New to this site; my inner cheese monster is very very glad I discovered it  :)

I initially came with a mozzarella problem...

I have a recipe which begins with melting mozzarella to the 'consistency of milk'.  I just tried to melt some, alone without milk or anything else (as instructed), and initially I got a small puddle of milk with lots of gooey mozzarella... which remained stringy and finally began to take on a yellow tinge when I tried to raise the temperature.

Any thoughts?  I have a relative who regularly makes this, with great success at the 'milky' stage!  She said it had to be 'fresh' mozzarella, and I confess that I used a fairly standard store-bought mozzarella, so I don't know if this may have contributed...

Any insight would be much appreciated :)  Thanks in advance!