ndbmemcache and fetching values with multiple columns as key (no replies)

Table structure:

dev.Stats
- UserID int
- StatName varchar
- Value varchar
UserID + StatName are the PK.

In ndbmemcache.containers, I have "UserID,StatName" as the key_columns, and "Value" as the value_columns. In key prefixes, I have "stats:" as the key_prefix, "caching" as the policy for this container.

However, I can't seem to access it via memcache.

I've tried 'stats:1,MyFirstStat', and nothing. The data does exist in the table, and I even tried using every ascii character upto 256 in place of the comma.