I have a unity express (NM-CUE)  version 2.2  , I want to upgrade this card to 7.0.1 ,

but when I  choice  ***  to upgrade and  write some infomation as below
ServicesEngine boot-loader> config                                            

IP Address [10.201.74.60] >                                                   

Subnet mask [255.255.255.192] >                                               

TFTP server [10.201.74.30] >                                                  

Gateway [10.201.74.1] >                                                       

Default Helper-file [cue-vm-k9.nmx.7.1.1.pkg] >cue-installer.nm-aim.7.0.1     

Ethernet interface [internal] >                                               

Default Boot [disk] >                                                         

Default bootloader [primary|secondary] [primary] >                            

above all can complete, but when I still doing this upgrade process not complete,, info as below

Please select from the following
1       Install software
2       Reload module
3       Disk cleanup
(Type '?' at any time for help)
Choice: 1
Package name: cue-installer.nm-aim.7.0.1 

Server url: ftp://10.201.74.30/
Username:
Password:

Downloading ftp cue-installer.nm-aim.7.0.1 

Bytes downloaded :  6373376
pycurl.error: invalid return value for write callback -1 2048

Error: Operation Aborted

who can tell me how can resolve this issue ..  or  tell me another salvation method  , many thanks ..