Using solver with loop

I recognize this is a common problem and I have researched the help forums but yet I cannot figure out what is knowing wrong. I am admittedly a novice when it comes to macros. I am trying to predict values for column "U" (mutiple rows) based on AI and the given constraint.

For now, I am getting a run 1004 error on the "Do While Not..." line, but I fear more errors are coming.

Thanks.

Worksheets("Beirut").Activate
Do While Not IsEmpty(Worksheets("Beirut").Range("U" & RowCount))
RowCount = 2
SolverReset
SolverOk SetCell:="AI" & RowCount, MaxMinVal:=1, ValueOf:="0", ByChange:="U" & RowCount
SolverAdd CellRef:="AJ" & RowCount, Relation:=1, FormulaText:="T" + RowCount
SolverOk SetCell:="AI" & RowCount, MaxMinVal:=1, ValueOf:="0", ByChange:="U" & RowCount
SolverSolve userFinish:=True
SolverFinish keepFinal:=1
RowCount = RowCount + 1
Loop
End Sub

Thanks much for the prompt response.

Unfortunately the suggested fix did not work. I am still receiving a Run-time error 1004 on the row starting with "Row Count = Range..."

I have uplodaed a file for help in clarification.Test.xlsx

Ok here is the file with the macro. As column U was empty it did not work using that column as a counter. I'm now using column T as the counter for the number of rows.

Before you can run the macro "Run_Solver" you must set a reference to solver in VBA.

Tab "Developer" -> "Visual Basic" -> "Tools" -> "References" and check that box "Solver" is ticked. If not you may have to browse for it. Normally found
\Microsoft Office\Office 12\Library\Solver\Solver.xlam

Alf