Setting Parameter Values To Equal DataColumn Values?

I'm trying to assign some parameters for a stored procedure with some values that are stored in a data table. in the code, I can set the parameter values to the data table, and give a column header or index without issue, but when it tries to execute at runtime it bombs out.the error I get is a variation on "Failed to Convert Parameter Value from a DataColumn to a String" depending on exactly how I try to assign the value.the data types are all correct elsewhere in the code.

my code for this bit is

Try
ConnectionAttempt.Open()
Try
With NewYearCommand_Dates

[code]....

other things I've tried to get this to work are all variations on the .Value=dates bit, such as

.Value=dates(0) (so using column index)
.Value=dates.columns(0) (again using column index)

I've also tried declaring variables, and setting their values to the values in the columns, but the code returns an error saying that "Value of type 'System.Data.DataColumn' cannot be converted to string".I should point out that i'm doing this for 3 tables at once in this sub, 2 of them will only have a single row of data, but the third has an indeterminate number of rows.I'm afraid I don't know what else to do. I'm lead to believe by my mate and my lecturer that this should work, and of course it will work, but the evidence says otherwise.