[Qgis-user] Problem with clip-tool

[BJSVW PraktiantIn AGI]

Dear QGIS users,

I`m using the f-tool plugin 0.5.3. Where I have some problems using the geoprocessing tool "clip" on polygon-layers. 
If I`m using the clip- tool on point - or line-layers, it all works fine. 


The problem: 

If I select a polygon-layer as input- and another polygon-layer as clip-layer the output is neither correct nor complete.
 
In the result of the clip process, some (obviously with the clip- layer intersecting) polygons of the input- layer are left out. 
Repeating the process with the same input- but a different clip- layer (which has intersecting areas with the clip- layer I tried first), the mistakes in the output change. There are left out the same or/and several other polygons. 

I`ve tried several combinations of input- and clip- layers. Every effort produced some mistakes. 


Does anybody know this problem? and knows how to fix it? 

thx, 

Corinne