Raymond,
Are you clicking on My Account thru the poker software and logging in there?
The best way to use Paysafecard to get it to work (trust me its happened to me) is to log in straight at
www.betfair.com. Log in on the top right hand side and then top right hand side where it shows your username and balance click the little button that says deposit and a smaller window opens up for you to deposit with.
I have tried to do it through the My Account section of Betfair but it wont let me it comes up with a page cannot be displayed after I have typed in the amount.
So try logging str8 into Betfair.com and logging in that way and depositing.
Any problems, give me a shout.