There are instructions on how to buy Sansar dollars that do not mention that this endeavour will fail if you haven't set up your account to enable access to US dollars FIRST. If there are instructions on how to do that, I failed to find them.
I successfully set up an account payment method, and successfully bought Sansar dollars, only to find that my attempt to buy Sansar dollars a second time failed and was cancelled by the system. If there is a limit on the amount that can be bought, or a time delay between attempts to buy, then that should be stated in the documentation.
As it is, it failed silently (ie, there was no warning that it had been cancelled by the system, I had to find that out by looking at my orders).