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Some necroposting here... huh
Got that very same problem with numbers. By doing source code research, I've found this piece of code in Standard.Data.aspx.vb would always return false for regional dot separator different than '.':
...
Public Overloads Overrides Function SetData(ByVal Argument As String) As String
...
If variables.ContainsKey("latitude") AndAlso IsNumeric(variables("latitude")) Then
point.Latitude = Double.Parse(variables("latitude"), System.Globalization.CultureInfo.InvariantCulture)
Else
point.Latitude = -1
End If
If variables.ContainsKey("longitude") AndAlso IsNumeric(variables("longitude")) Then
point.Longitude = Double.Parse(variables("longitude"), System.Globalization.CultureInfo.InvariantCulture)
Else
point.Longitude = -1
End If
...

Module author sets the value of 'variables("longitude")' to invariant representation with javasript code (in Map.js) directly converting to '.' separator and then tries to check that value with IsNumeric function which is culture-aware. Hence, there will always be false result for cultures whose digital separator not set to '.'.

Hope that will help someone. And may be module author will patch this bug out someday.

ps Sorry for my english