Negotiate over the phone or at the property?

[Jonathan Guerrero]

I've talked several prospects about selling me their property and they never tell me what they want upfront.  I know they have a certain number in mind and I let them know that, however they never give in.  I tell them that I will give them my offer and when I do they're shocked it's so low.  Some sellers are in the ballpark and I have done a good job at negotiating there. 

Now I don't know if this is hindering my chances of getting a deal under contract.  Are the chances of getting a deal higher if you meet in person, walk the property and negotiate or does it not matter?