Queries :: How To Count Unique Dates

I want to do a unique count of dates when an activity was done in my table. The table may have multiple entries of the activity performed possibly on the same date by an individual

e.g. table entries

Code:

approvalNoSys dateAssessed Activity
100 01/08/2015 Audit
100 01/08/2015 Audit
100 01/05/2015 Audit
100 01/05/2015 Audit
100 01/02/2015 Audit
100 01/01/2015 Audit

Unique audit Count must equal 4

Code:

totV = ECount("[dateAssessed]", "R_P_Data_P", "[approvalNoSys] = '" & [Forms]![cmrOverview]![txtappNoSys] & "' AND [Activity] Like '*audit*'")
totV = Unique count
dateAssessed = date field in R_P_Data_P table
R_P_Data_P = table
"[approvalNoSys] = '" & [Forms]![cmrOverview]![txtappNoSys] & "' = criteria for the customer in question to separate them from many other customers in the table.
Activity = text field in R_P_Data_P table
audit = the activity

I'm also trying to avoid having to build total queries etc to them reference them, I'd like getting the desired outcome in an expression or small code.

I read about Ecount but my complier doesn't recognise the function