[jQuery] jQuery functions called from setTimeout fails

[Mike]

I have a jQuery function with three parameters which works just fine
when invoked directly,

           movebus(a,b,c);

but when I try to delay its invocation using setTimeout, as in

           setTimeout("movebus(a,b,c); ", 5000);

I receive the error message in Firebug "movebus(a,b,c) not defined".

Can anyone suggest why this is?

regards

Mike