For loop in xml template

[ksj]

I am attempting to use the documented for loop in an xml template and am getting an error that says:

Invalid parameters or processing instruction for

This is the section where I am using the loop:

<interface xmlns="http://tail-f.com/ned/cisco-nx">
<mgmt>
<name>0</name>
<description>{$mgmt_description}</description>
<vrf>
<member>management</member>
</vrf>
<ip>
<address>
<ipaddr>{$mgmt_ip}</ipaddr>
</address>
</ip>
</mgmt>
<Vlan>
<name>1</name>
<shutdown/>
</Vlan>
<?for i=1; {$i < 55}; i={$i + 1}?>
<Ethernet>
<name>1/{$i}</name>
<enable>
<switchport>false</switchport>
</enable>
<description>Auto_Cable_Testing</description>
<ip>
<address>
<ipaddr>192.168.{$cable_test}.{$i*2}/31</ipaddr>
</address>
</ip>
<flowcontrol>
<receive>off</receive>
<send>off</send>
</flowcontrol>
</Ethernet>
<?end?>
</interface>

Any ideas on what I'm doing wrong?

TIA

[aelganzo]

the for loop is correctly defined, So the questions did you add mgmt_description, mgmt_ip and cable_test variables to your python?