Hi,
There is an issue with the SEF on your website.
When the control panel of HikaShop checks that the user is logged in and finds that it's not the case, it adds that please login first message and redirects to the login URL of the com_users components. Here is the code doing that:
monosnap.com/file/LC6ZGPqfN7tEh3mT787cF3Qdh2CotZ
However, on your website, when I click on the "my account" menu item, I get redirected to the URL /logout?return=aHR0cHM6Ly90ZXN0LmxlY29uY2VwdHMuY29tL215LWFjY291bnQ= :
monosnap.com/file/K20as2JLcPUjiC1fxhEKccDyFlCPQB
So there is a problem because that $url = 'index.php?option=com_users&view=login'.$url; shouldn't be SEFed by Joomla to /logout?return=aHR0cHM6Ly90ZXN0LmxlY29uY2VwdHMuY29tL215LWFjY291bnQ=
I'm not sure why it's doing that. Maybe you're using a SEF extension like sh404SEF and it messes with that, or there is something else which changes the URL like a system plugin or some customization.