Custom Bank Payment page

Hi,
I just buy prosite plugin to make a network blog. I install plugin, activate it.
Everything seem to be Ok if i let payment with paypal.
If i change it to Stripe i've got a blank page everywhere, and error in my error.log:
[Tue Sep 04 10:55:54 2012] [error] [client 83.206.29.91] PHP Warning: Creating default object from empty value in /home/chirurgien-dentiste.me/public_html/wp-content/plugins/pro-sites/pro-sites.php on line 3313, referer: http://chirurgien-dentiste.me/pro-site-3/
[Tue Sep 04 10:55:54 2012] [error] [client 83.206.29.91] PHP Warning: number_format() expects parameter 1 to be double, string given in /home/chirurgien-dentiste.me/public_html/wp-includes/functions.php on line 155, referer: http://chirurgien-dentiste.me/pro-site-3/
[Tue Sep 04 10:55:54 2012] [error] [client 83.206.29.91] PHP Warning: number_format() expects parameter 1 to be double, string given in /home/chirurgien-dentiste.me/public_html/wp-includes/functions.php on line 155, referer: http://chirurgien-dentiste.me/pro-site-3/
[Tue Sep 04 10:55:54 2012] [error] [client 83.206.29.91] PHP Warning: number_format() expects parameter 1 to be double, string given in /home/chirurgien-dentiste.me/public_html/wp-includes/functions.php on line 155, referer: http://chirurgien-dentiste.me/pro-site-3/
[Tue Sep 04 10:58:05 2012] [error] [client 83.206.29.91] PHP Warning: Creating default object from empty value in /home/chirurgien-dentiste.me/public_html/wp-content/plugins/pro-sites/pro-sites.php on line 3313, referer: http://chirurgien-dentiste.me/pro-site-3/

what i can do to solve it ?

And I'm wright to use "strip" to made my custom payment page with my bank account directly (not using paypal) ?

Thanks for the help.