What do i do,i want to talk to my sister?

iam 22 years old and all my life knew my bio father who i just recently started talking to.. had another daughter younger then me with another woman... well i figured she now about 16 and could handle knowing about me also so i did some detective work online and found her ... she never knew about me which i figured so i spoke with her mom and all seemed ok she said i could meet her around xmas when they came upstate now to no avail no calls no emails nothing i really wanna just talk to my sister and find out from HER if she wants a reletionship not her mom i feel like im being lied to what should i do