In your options go in the control section make sure the keyboard set up in the bottom right corner is set to YAP controls and thrust vectoring is set to up/down arrows.The use the up/down in the game when lined up on the tanker.You may have to re-install the photo recon/refueling mod after you have changed any control settings. There is a post in these threads about refueling if thats no help try
http://www.yankeeairpirate.net/Faq.asp.Nick.