Error 53 "Manager Call Not Supported" for write PNG file VI on RT

[smarlow]

I'm getting the "Manager Call Not Supported" when attempting to save a PNG file on an NI Phar Lap ETS target.  It's nice that the RTOS supports the "Get Image" method for control references, but being unable to save a PNG image makes that method pretty useless.  The "write BMP file" VI works just fine, but who wants to generate HTML with BMP images?  Is there a solution to the PNG vi, or has someone written an alternative?  Thanks.