title: NSInvocation: unrecognized selector though it is set
body: <p>I'm getting this message:</p>
  
  <p>"(null): unrecognized selector sent to class 0x3f52e824"</p>
  
  <p>The basic code I've tried:</p>
  
  <pre><code>SEL sel = @selector(applyProperties:toObject:);
  
  NSInvocation* inv = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:sel]];
  [inv setTarget:self];
  [inv setSelector:sel];
  [inv setArgument:params atIndex:0];
  [inv setArgument:theObject atIndex:1];
  
  NSOperationQueue* queue = [[NSOperationQueue alloc] init];
  NSInvocationOperation* operation = [[NSInvocationOperation alloc] initWithInvocation:inv];
  [queue addOperation:operation];
  
   [queue release];
  </code></pre>
  
  <p>I can call (applyProperties:toObject) by itself with these arguments... so I'm not sure what I'm doing wrong.</p>