What triggers the parameter input box on a query

[AccNovice]

I have the following query:

SELECT [20 AGENTS].PER, [20 AGENTS].BRANCHKEY, Sum([20 AGENTS].GWPREM) AS GWPREM, Sum([20 AGENTS].GEPREM) AS GEPREM, Sum([20 AGENTS].GCINC) AS GCINC, Sum([20 AGENTS].NWPREM) AS NWPREM, Sum([20 AGENTS].NEPREM) AS NEPREM, Sum([20 AGENTS].NCINC) AS NCINC
FROM [20 AGENTS]
GROUP BY [20 AGENTS].PER, [20 AGENTS].BRANCHKEY
HAVING ((([20 AGENTS].PER) Between [Start Period for Agent Balance] And [End Period for Agent Balance]) AND (([20 AGENTS].BRANCHKEY) Like "*COMPA*"));

When you run the query you get pop-up boxes that request you to fill in the Start Period and End Period. My question is - What on the query trigger these pop-up boxes?

 

[wazz]

Between [Start Period for Agent Balance] And [End Period for Agent Balance]

the stuff in the brackets. if they aren't fields in a table, popup.

 

[AccNovice]

Thanks you very much for the feedback. The stuff in the brackets is not on a table.
Thanks my question was answered.

 

[wazz]

your welcome. dig your replies.