problems aquiring signal

[Pells]

I'm trying to aquire a signal from a pressure sensor, I try to get the signal as the difference between 2 voltage pins, so I use a differential measurement. The card I use is a 6025E 

When I look at the signal through a differential amplifier and in to an oscilloscope I see it just fine.

And when sending a similar signal from a function generator to my 6025E card I can aquire that without any problems so individually my system is working. But when I try to aquire the real signal with my card this is not working, I get a totally different signal with lots of disturbences and strange things in it.

The two pins are individually giving out about 5V and the difference is in the range -50mV to 50mV

Any ideas on what could be causing my problems?

I am using the DAQ-assistent in labview to controll my card.

One question I have is why I need to choose "samples to read" even though I aquire the data continuous? It seems like this parameter has a very large effect on my results...so how does this effect the measurements and can I get rid of it's effects?  

Also it effects how I see the signal in my graph in labview, I mean if I choose a small samples to read value I don't even see one whole period, so can't I just aquire it continuous and see it continuous in my graph just like I would in an oscilloscope?

[Pells]

here is my VI...it's very simple but maybe you can see any problems in it?

[devchander]

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But when I try to aquire the real signal with my card this is not working, I get a totally different signal with lots of disturbences and strange things in it.

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The signal connection might be the source of this concern

Read this link to know more on connecting signals to a  DAQ card

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One question I have is why I need to choose "samples to read" even though I aquire the data continuous? It seems like this parameter has a very large effect on my results...so how does this effect the measurements and can I get rid of it's effects?  

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it does not effect your measurement accuracy, it merely determines how many samples are read out from your AI buffer and hence determines your loop rate.

If you set it equal to sampling rate, your loop will perfrom 1 iteration per sec and read all samples scanned in one iteration itself

If you set it as half of sampling rate, your loop will perform 2 iterations per sec and reads half the total number of samples to be acquired/ sec, in each iteration