Need example of usage DerelictPQ

[Suliman via Digitalmars-d-learn]

I have done next:

	string connString = "psql -h localhost -p 5432 -U postgres -d 
testdb";
	package PGconn* conn;
	@property bool nonBlocking(){ return PQisnonblocking(conn) == 1; 
}

	this(parseConfig parseconfig)
	{
		void connect()
		{
			try
			{
				DerelictPQ.load(getcwd ~ buildPath("\\libs\\libpq.dll"));
				
				conn = PQconnectdb(toStringz(connString));
				if( !nonBlocking && PQstatus(conn) != 
ConnStatusType.CONNECTION_OK )
				throw new Exception("Can't connect to DB");


			}
			catch ( DerelictException de )
			{
				writefln("Failed to load libpq.dll: %s", de.msg);
			}



		}
		connect();

But it runtime I am getting next error:

object.Exception at source\app.d(203): Can't connect to DB
----------------
0x00402D31 in 
D3app10PostgreSQL6__ctorMFC3app11parseConfigZ7connectMFZv at D:\Pr
oject\2014\seismoDownloader\source\app.d(203)
0x00402C3F in app.PostgreSQL 
app.PostgreSQL.__ctor(app.parseConfig) at D:\Projec
t\2014\seismoDownloader\source\app.d(216)
0x0040208B in _Dmain at 
D:\Project\2014\seismoDownloader\source\app.d(30)

What I am missing? Where I can to look right format of connection 
string for this driver?