I can't use scaled coordinates with BarChart:

Placed::labpos: "!("Inside") is not a valid position for the placement of labels.

 Module[{labels = {"HSTM", "SCOPUS", "ISI", "PubMed"}, 
 data = {0, 13, 39, 25}}, 
 BarChart[data, ChartLegends -> Placed[labels, {0.9,0.8}], 
 ChartStyle -> {RGBColor[0, 0, 0], RGBColor[0.8, 0, 0.2], 
 RGBColor[0.3, 0.8, 0.2], RGBColor[0, 0.3, 0.7]}, 
 PlotRange -> {{0.5, 4.5}, {0, 40}}, Ticks -> {None, None}, 
 AspectRatio -> 1.5, Frame -> {{True, True}, {True, True}}, 
 FrameLabel -> {Style["", FontSize -> 18], 
 Style["nº de publicaciones", FontSize -> 18]}, 
 FrameTicks -> {{{0, 10, 20, 30, 40}, None}, {None, None}}]]

Does anybody know how can I fix this?