text-objects for module and methods don't work

I'm having trouble with the module and method text objects.
```
    im
    am
    iM
    aM
```
When I try to invoke one of them (say `vam`) I get the error message:
```
E117: Unknown function: <SRN>106_wrap_a
````
or ```E117: Unknown function: <SRN>106_wrap_i``` for `vim`

I have the necessary plug-ins loaded and `var` and `vir` work.

How do I troubleshoot this?