miner run ubuntu got 500 error

[supercanada1]

I run ubuntu VPS and installed miner for X15, linux version,
when I run the miner,
./minerd -a bitblock -o localhost:23741 -u username -p password

it shows error: Http request failed, the requested URL returned error 500

What happend? do I need to install a web server such as apache?, since "Http request failed"