after download bitsream mdm connection lost

Hi!
I have a problem regarding Cable drivers on my Linux system. I am using 
CentOS 6.4 -64bit. The point is, that the Cable drivers are working for 
one time and I can download a bitstream on my FPGA. I can also open the 
XMD to download for example an .elf. Then I want to use the connection 
to transfer a Linux image (more precisely a PetaLinux image via 
petalinux-jtag-boot, which transfers via XMD tool as well), but then it 
says unable to transfer and my system is not able anymore to detect the 
cable...
Can anyone help me?