Sub CalculateStorageCharge()

Dim datedue, datecollected As Date

Dim daysoverdue As Integer

Dim storagechargetotal As Integer

Dim storagechargefeeperday As Integer = 5.0

daysoverdue = DateDiff("d", datedue, datecollected)

If (daysoverdue) > 0 Then

storagechargetotal = (storagechargefeeperday * daysoverdue)

Else : storagechargetotal = (0 * storagechargefeeperday)

End If

storagechargetotal = CInt(txtStorageChargeFee.Text)

End Sub

Conversion from string "" to type 'Integer' is not valid. appears on the line:

storagechargetotal = CInt(txtStorageChargeFee.Text)

if anyone can help me with this problem it would be greatly appreciated as i have been trying to solve this problem for some time and am a beginner when it comes to VB