constraint

[sandrissss]

why does inventor rejects this constraint?

[cwhetten]

An assembly file (IAM) is useless without its part files (IPT).  Zip the assembly with its part files and attach.

[ampster401]

you may also want to state what version of Inventor you are using so people don't waste time downloading your files just to find out they can't open them or perhaps provide you with file/s that are useless to you if their files are newer than what you can open.

[Cadmanto]

Also providing some images along with a more detailed posting of what you are trying to do, what you are trying to accomplish and what you hope to achieve never hurts.

[sandrissss]

o, ok didn't thoght about that. version- autodesk inventor professionale 2012. There are only one way how to constrain those 2 parts, so i think everyone wil understand without images

[hunt]

You attached the IDW file instead of the IPT file.

[cwhetten · Accepted solution]

Your holes on each part are not the same distance apart--they don't line up.  See the first image where I measured the distance between the hole axes--note the value of the measurement.  When you apply the insert constraint with an offset of 0, you are telling Inventor to align the axes of the holes so that their offset is exactly 0.  If the hole spacing on the black part is not EXACTLY the same as the hole spacing on the sheet metal part, then that constraint will fail.

The reason is clear when I look at the feature where you created these holes.  The sketch is not fully constrained!  If it isn't constrained and dimensioned, how do you know where the holes are?  See the second image--the light blue in my color scheme indicates under-constrained sketch geometry.

Your sketches should be fully constrained and dimensioned so that there are no degrees of freedom.  Take some extra time to practice sketching with proper techniques.  Sketching is so fundamental to working with Inventor--if you don't learn to do it right, you will only find more errors and frustration in the future.

And just keep asking questions!  There are plenty of people here that can give you some help.