help - simple problem please....

[admin]

This is driving me nuts; I am having trouble with the following simple script:

function checkform()
{
var check = this.document.Workplan;
if ((check.request.value=="") || (check.cash.value=="") || (check.inkind.value==""))
{
alert("Please enter all required fields.");
check.request.focus();
return false;
}
check.submit();
}

It says "object does not support this property or method" referring to the "check.submit();" line. Why not? I can get the form to submit without validation (using a submit button)...

The form is named "Workplan" (case matches), has proper start and end tags?

Thoughts? Thanks so much for your help.