SQL & PL/SQL

Does anybody know whether there is a setting on a procedure to set all input parameters as required? And if there is then can it be turned off? I have a procedure B that is called from procedure A. Proc B requires several parameters to be passed, however not all of them are used for each individual call to Proc B from Proc A.

If I call Proc B from Proc A like this:

ProcB('', 'value2', '', 22, '', 87);

then it works fine. However if I attempt to pick and choose the parameters like below then I get a compilation error complaining about PLS-00306: Wrong numbe or types of arguments in call:

ProcB(vParam2 =>'value2', nParam4 => 22, nParam6 => 87);

Question is: does this mean it is not possible to use the 'pick and choose' => method? Or is the Procedure B set somehow that its input parameters are all required, and can this be changed?

Many thanks