[VBA] Operation not allowed for this type of object.

Hello,

I recently learned Visual Basic, but now that I'm using it with Access, I'm having some issues, particularly because I want to refer to fields in tables, etc., which is not the same as with Excel and I'm having a bit of trouble. So I hope you can forgive me if you ever find my mistakes to be glaring.

Before explaining my problem, let me outline the setup:

I have a table named "t_Card" containing a column named "i_Card" (which corresponds to the primary key of this table).
I have a second table named "t_Channel" that also contains the column "i_Card"; these are two linked tables, and for each value of i_Card in the t_Card table, there corresponds one or more records in the t_Channel table.

I would like to count the number of non-empty records in the t_Channel table for each value of i_Card in the t_Card table, and then assign this number to a new column in the t_Card table for each record.

(Sorry if I'm not explaining myself well, but basically I would like to display for all records in the t_Card table the number of non-empty records that correspond to them in relation to the t_Channel table)

Here’s the code I’ve written:

Sub essai()
Dim Card As Object
Dim t_Card As DAO.TableDef
Dim db As DAO.Database
Set db = CurrentDb
Set t_Card = db.TableDefs("t_Card")

For Each Card In t_Card
'For each record in the t_card table, i takes the value of i_card from the t_card table and
'assigns the variable nbre_channels_occupes to the channels_occupes field of the t_card table
i = i_Card.Value
'Count the total number of channels in the t_Channel table for t_card.i_card=t_channel.i_card
nbre_total_channels = DCount("[i_Channel]", "t_Channel", "[i_Card] ='& i&'")
'Count the number of empty channels in the t_Channel table for t_card.i_card=t_channel.i_card
nbre_channels_vides = DCount("[i_Channel]", "t_Channel", "IsNull([i_Signal_input])")
'Calculate the number of occupied channels in the t_Channel table for t_card.i_card=t_channel.i_card
nbre_channels_occupes = nbre_total_channels - nbre_channels_vides
'For each value of i_Card from the t_Card table, the Total_Channels field takes the value of the variable nbre_channels_occupes
If t_Card.Fields("i_Card") = i Then
t_Card.Fields("Total_Channels") = nbre_channels_occupes
End If
Next Card

End Sub

The issue arises at the "For Each...", here's the error I get:

Operation not supported for this type of object.

Could you please indicate a solution? Thank you very much!