Rastislav Vyletel

I have connected MDO34 via USB and I am using VISA in .net windows form application. 
I would like to capture a screen of oscilloscope directly in my application as binary block of bytes.  
IDN? query works. 

but reading data throw exception: "The binary block header was not found in the input stream"
When I use another application for those SCPI comands:
"SAVe:IMAGe:FILEFormat PNG"
"SAVe:IMAGe:INKSaver OFF"
"HARDCopy STARt"

I can see returned raw data from oscilloscope.

When I connect another osciloscope (not form tektronix ) and I use command 
":DISPlay:DATA? BMP, COLor"
I am able to read data via  ResultsArray=formattedIO.ReadBinaryBlockOfByte();
but not form Tektronix MDO34.

I suspect Ivi.Visa driver. please help me how to solve this problem.