Problems with paypal

Dear Sirs,

We are testing all the features of Hikashop Basic with the idea to pass to Business Version as soon as possible.

But we are founding an important and strange issue that is blocking us: with a completely new version of the website, everything works properly, but for we are testing two products: one works in all the conditions and the payment is completed, and the other one sometimes works and sometimes not!

It does not pass from created to confirmed status, even if the payment process seems to be the same and complete. It is very strange that sometimes works and sometimes does not.

Here with attached you will find the screenshot of the products. Test 1 works in all condition and test 2 does not.

Any idea?
We saw that wit 0,01 - 0,04 prices it works, but as we move to 100 euro price it stops to work.

Thanks
Mapi

If active debug mode,

no log files written in comes in the payment log file
folder permissions are 777

I also tried to disablethe "Return method" option.

with the same result!

I looked in the log file of the server, these are the lines on the payment

173.0.XX.XXX - - [13/Dec/2012:06:03:15 -0500] "POST /index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=paypal&tmpl=component&lang=it&Itemid=819 HTTP/1.1" 200 4049 "-" "-"

....

173.0.XX.XXX - - [13/Dec/2012:04:14:14 -0500] "POST /index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=paypal&tmpl=component&lang=it&Itemid=803 HTTP/1.1" 200 4063 "-" "-"

...

173.0.XX.XXX - - [13/Dec/2012:04:08:56 -0500] "POST /index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=paypal&tmpl=component&lang=it&Itemid=803 HTTP/1.1" 200 34 "-" "-"

thanks