Solve mystery bug with API -- 2

I have successfully used the private API to get my balance at TradeSatoshi.com. However, when I try to use it to place a trade, I get an HTML redirect to the login page instead of an API response. This appears to be a bug in the API. (My Perl code and some PHP code I found on the web have the same issue.) I have tried to get support multiple times from the site and help can't figure out what I'm talking about (presumably some non-tech person is doing customer support.) I know it is possible to use the API to trade because sometimes my manual trades are matched by an API trade. Your job is to solve the mystery. I will supply the nearly working API code in Perl. I can supply a very nominal amount of cryptocurrency (worth less than 1¢) for your testing on your acct if needed.