xmodmap on Xubuntu 11.04 - X error of failed request

[Maximilian Matthé]

Hello,

I have just installed xubuntu 11.04 on my pc, where xubuntu 10.10 was
previously running. 

In 10.10 I had a script called ~/.swapctrlalt that swapped the left ctrl
und alt-keys. It worked fine. It does not work in 11.04 anymore:

,----
| mmatthe at MatteLP:~$ xmodmap -pke | egrep '(Control|Alt)'
| keycode  37 = Alt_L NoSymbol Alt_L
| keycode  64 = Control_L NoSymbol Control_L
| keycode 105 = Control_R NoSymbol Control_R
| keycode 204 = NoSymbol Alt_L NoSymbol Alt_L
| mmatthe at MatteLP:~$ cat .swapctrlalt
| clear control
| clear mod1
| keycode 64 = Control_L
| keycode 37= Alt_L
| add control = Control_L
| add mod1 = Alt_L
| mmatthe at MatteLP:~$ xmodmap .swapctrlalt
| X Error of failed request:  BadValue (integer parameter out of range for operation)
|   Major opcode of failed request:  118 (X_SetModifierMapping)
|   Value in failed request:  0x17
|   Serial number of failed request:  15
|   Current serial number in output stream:  15
| mmatthe at MatteLP:~$ 
`----

I hope you can help me, because I really need to swap those keys. I can
swap them in Unity using the GUI for the keyboard, but I need it in XFCE
also. 
Regards, Max