Open Source Document Management System | OpenKM

I have the following PHP code to help me to import scanned images into OKM:
I intended to add the keywords "SCAN" and "PDF" once inserted. However, it appears as "SCAN, PDF" in OKM instead of 2 words. I also tried:
'keywords' => "SCAN, PDF"
'keywords' => "SCAN PDF"
'keywords' => 'SCAN, PDF'

and without luck. Can someone show me the correct syntax please?

Thanks!

The 'SCAN, PDF' should be and array not a String ( something like array("scan", "pdf"") )

It works! Thank you!