Reference a control in a subform from a module

[sponge]

Hi,

I'm trying to reference a control in a subform from a module but I keep getting errors!

Here's what I've tried.. and what error I've been getting:

First try:
GetCboEntries = Forms.frmMain!frmSub.Form![cboEntries].Column(1)
(where frmSub is the name of the actual form in the subform control)
Error: Object doesn't support this property or method

Second try:
GetCboActivities = Forms.frmMain!chdMain.Form![cboEntries].Column(1)
(where chdMain is the name of the subform control)
Error: Object doesn't support this property or method

Third try:
GetCboEntries=Forms!NameOfMainForm!NameOfSubform![cboEntries].Column(1)
Error: Run-time error '2450':
Microsoft Access can't find the form 'frmMain' referred to in a macro expression or Visual Basic code.

Any help would be much appreciated!

Thanks in advance!