Object doesn't support property 'print'

Question

Currently i have an iframe with a pdf file embed and i wanted to print this pdf, but when i tried to print it it shows me the next message: Object doesn't support property 'print'.

This is my current iframe code:

<iframe height="329" id="pdf1" src="file.pdf" style="width: 100%;" type="application/pdf"></iframe>

And this is my javascript code:

document.getElementById("pdf1").focus();
document.getElementById("pdf1").print();

This is the way some sites recomended but still have no success. My current PDF reader is Acrobat.

Thanks in advance