I have a similar issue. I am using Joomla 3.4.0 with VirtueMart 3.0.2 and the Clean Mart template. I also have the two shipment plugins from iStraxx UG - the Vm Shipment - UPS version 3.09 and the Vm Shipment - USPS version 2.12 and I have the standard shipping method enabled for Weight/Countries.
If I disable your shoppng cart and use the standard VM cart I can select any Shipment Method and all works as expected.
With your Shopping Cart enabled here is what happens:
I see the following available Shipping Options in the cart when I click on Select Shipping
- Standard Shipping
- UPS Ground ($11.76)
- UPS Three-Day Select® Guarantee Day Delivered in 3 Day(s) ($20.22)
- US Postal Service First-Class Mail Parcel ($5.32)
- US Postal Service Priority Mail Express 1-Day Flat Rate Boxes ($47.95)
If I select Standard Shipping and then Save - it works fine and this shipping method is selected.
If I select UPS Ground ($11.76) and then Save the result is that UPS Three-Day Select... for ($20.22) gets selected.
If I select UPS Three-Day Select® Guarantee Day Delivered in 3 Day(s) ($20.22) and then Save - it works fine and this shipping method is selected.
If I select US Postal Service First-Class Mail Parcel ($5.32) and then Save - nothing happens, nothing is selected.
If I select US Postal Service Priority Mail Express 1-Day Flat Rate Boxes ($47.95) and then Save - nothing happens, nothing is selected.
Keep in mind that these all work perfectly if I am not using your cart.
Let me know if you want access to the Admin side of the site...