[OpenMesh] inf values in texture coordinates when writing obj file

Hi. I have problem with UV texture coordinates of vertices stored in obj file after writing mesh to obj file. I set UV coordinates for a vertex using method set_texcoord2D(). When explore the resultant obj file I see some inf values in 'vt' lines of the file. The UV values I set from code have no inf values. What could be the problem? Thanks, Vladimir Privalov