problems with sending zpl in POST request to ZT420

Hello all,


we integrate the "printing to networked zebra printer" sample from

blog post in our web site.

It works as long the zpl is simple and small. But when we use our real world zpl (ca. 4kBytes), no label is printed.

The printer responds with HTTP Code 200 (OK), but no printing is done.

We are not sure where the problem is, because the same zpl send over the USB cable to the printer (using Zebra setup utilities) is printed without problems.

Therefore we assume that the syntax of the ZPL is OK.


Any hints where to search the error ?


Regards, Frank