Minecraft command block not outputting for /testfor command [duplicate]

My problem is what the title specifies. I'm creating an adventure map with an xp store. I have a series of command blocks which check for the proper xp level, take away the cost of the item and give the player that item. however when I go to check my xp level with /testfor, the command block doesn't output anything. instead it tells me

[19:54:57] /testfor < player>

The command I put in was /testfor @p [lm=5]

I tried moving [lm=5] so it was right beside the @p, but Minecraft told me it can't find the player. I also tried putting my playername in, but I got the same output from before. Is there something I'm missing here?

Solution 1:

Target selector parameters must be placed directly next to the selector, with no space between them. "lm" stands for "level minimum", and it if's telling you it can't find the player, that means no player with 5 XP levels or more was found.

The correct command is:

/testfor @p[lm=5]

Also note that selector parameters can only be used with a selector. Using playername[lm=5] is invalid syntax. To check for a specific player along with parameters, you must use the name parameter:

/testfor @p[name=playername,lm=5]