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<P><FONT SIZE=2 FACE="Arial">Using Access97 on Windows 2000.</FONT>
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<P><FONT SIZE=2 FACE="Arial">I have three tables from which I want to display related data on a single form. </FONT>
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<P><FONT SIZE=2 FACE="Arial">The tables are hierarchically related: </FONT>
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<P><FONT SIZE=2 FACE="Arial">tblProjects is the uppermost parent</FONT>
<BR><FONT SIZE=2 FACE="Arial">tblPhases contains child records related to specific records in tblProjects</FONT>
<BR><FONT SIZE=2 FACE="Arial">tblMilestones contains child records related to specific records in tblPhases</FONT>
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<P><FONT SIZE=2 FACE="Arial">My approach so far has been to create an unbound main form with three combo boxes - one for each table in the hierarchy, returning the table's primary key - and then to embed a single-form subform for each table in a tab control. The idea is that the user will select the project from cboProjects, cboPhases will re-populate according to the selection, the user can then select a phase from cboPhases, and cboMilestones will re-populate according to that selection, and the subforms will be synchronized with the values chosen in the combos. </FONT></P>
<P><FONT SIZE=2 FACE="Arial">Seems simple, and it works well enough when simply displaying data. However, I also want to allow new records to be added to any of the three subforms. Here's where I run into trouble. When I attempt to add a new record to a table via the subform, I get an error: "You tried to assign the Null value to a variable that is not a Variant data type." I have minimal experience with bound subforms in an unbound main form, but I suspect that the error is related to something internal to Access as it attempts to synchronize the subs with the parent form. I say this because no code of mine is executing at the time the error occurs, and I have found no means of capturing the error. The maddening thing is that, when I clear the message box, the record is added as expected with no errors.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">I'm hoping that somebody knows where this error is happening so that I may trap it and bypass the message box. Failing that, perhaps there's a more effective way to accomplish what I'm trying to do. Either way (or maybe both ways!) I welcome any advice, suggestions, comments, or further questions.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Thanks!</FONT>
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<P><FONT SIZE=2 FACE="Arial">Don McGillivray</FONT>
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